Campaign menu and story: mission list, briefings, goals panel, mission end flow

- Title screen: Campaign with the list of the 20 missions (done / open / locked)
- Briefing per mission: story told by old Crookfinger (EN/DE), goals, new tools,
  creatures and gold carried over; start button
- In the game: goals panel with progress (click/tap opens the briefing again), the pause menu
  has a Briefing entry to read the whole briefing again
- Mission end: next mission / try again and back to the campaign; won missions and the
  carry-over are stored in the browser; epilogue after the last mission

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en.lang

@@ -431,3 +431,75 @@ msg.mission_won = Mission accomplished!
 msg.time_up = Time is up - the knights have secured their treasures.
 hud.time_left = Time
 msg.tool_locked = This is not available yet in this mission.
+
+# campaign menu and goals
+menu.campaign = Campaign
+menu.goals = Briefing
+camp.goals_panel = Goals (click: briefing)
+camp.title = The Broken Core
+camp.locked = ???
+camp.progress = {0} of {1} missions accomplished
+camp.mission_title = Mission {0}: {1}
+camp.goals = Goals
+camp.time_limit = Time limit: {0}
+camp.new_tools = New: {0}
+camp.carry = Coming along from the last mission: {0} creatures and {1} gold.
+camp.start = Start
+goal.shards = Take back the shards
+goal.heart = Destroy the gate of the order
+goal.killall = Defeat all knights
+goal.loot = Take {0} from the knight vaults
+goal.towers = Raze all knight towers
+goal.survive = Beat {0} waves
+goal.left =  ({0} left)
+end.mission_won = Mission accomplished!
+end.mission_won_sub = Crookfinger nods approvingly. Your strongest creatures and a fifth of the gold come along into the next mission.
+end.mission_lost = Mission failed
+end.mission_lost_sub = The knights are celebrating. Crookfinger suggests you try again - he has already sharpened the shovel.
+end.again = Try again
+end.next = Next mission
+end.campaign = Campaign
+end.to_campaign = Back to the campaign
+
+# campaign story: told by old Crookfinger, the imp advisor (" | " starts a new paragraph)
+camp.m01.title = A Shard in the Dark
+camp.m01.story = Wake up, master. Yes, you. A hundred years ago the Order of the Lightwatch smashed your soul core and carried the shards off like trophies. What is left of you fits into one small cave, four imps and me - old Crookfinger. | The knights keep the first shard in a little outpost to the east, guarded by recruits who still believe in polished boots. Dig a way there and let your imps claim the shard chamber. Knight ground takes them a while to claim, and not while knights stand next to it.
+camp.m02.title = The Border Brook
+camp.m02.story = A brook! Underground! The knights think a bit of water keeps us out. Charming. | Build a bridge across it - wood is cheap, knight pride is not. The watch post on the far bank holds the next shard, and this time it has an arrow tower. Towers do not chase you: stay out of range or let your creatures tear them down.
+camp.m03.title = The Guardhouse
+camp.m03.story = The Lightwatch keeps a guardhouse here where young knights learn to march in circles. They call it patrolling. We call it a timetable. | Learn it, strike when they turn their backs, and wipe out the whole garrison. A training room is finally yours - training makes creatures stronger, but the bill comes on payday.
+camp.m04.title = The Order Strikes Back
+camp.m04.story = Well, that got their attention. The Order sends wave after wave from its gate to put out the little fire in the dark - us. | Four waves, then they run out of volunteers, or at least of enthusiasm. Build arrow towers, keep the lightning ready and do not let them touch the core.
+camp.m05.title = The Gold Chambers of Hellwatch
+camp.m05.story = Hellwatch is where the Order keeps its pay chests, which explains why the knights here are so cheerful: they get paid. | Their vaults hold gold, silver and even gems. Claim the vault chambers and the treasure is yours. Six thousand should cover our expenses. And our hurt feelings.
+camp.m06.title = The Bridge of the Lightwatch
+camp.m06.story = The Lightwatch built a bridge over the great river and put a gate at its end, with a banner that has a sun on it. Of course it has a sun on it. | Destroy the gate of the order and the outpost collapses into polite panic. They brought cannons, by the way. Cannons push your creatures around - keep them close together.
+camp.m07.title = Lava Ground
+camp.m07.story = Lava ground. Warm, cosy, a bit too bright. Wooden bridges would burn here, so you build stone ones: dearer, but fireproof. | Whatever is pushed into the lava is gone for good, knights included. Especially knights. The shard lies in the fortress beyond the glow. And a torture chamber is open to you now - some prisoners can be persuaded to change sides.
+camp.m08.title = The Raid
+camp.m08.story = A raid! No shard today, just cash. Two vault keeps, stuffed with the tithes of the Order. | You have fifteen minutes before they bring their treasure to safety, and a few hired thugs to get going. Take eight thousand worth from their vaults. Quickly, master - Crookfinger has debts.
+camp.m09.title = The Twin Keeps
+camp.m09.story = Two keeps on both banks of a river, each guarding a shard. The knights call them the Brothers. One brother fusses about his boots, the other about his hair. | Take both shards. The river has knight bridges: claim them, or the knights will use them to visit you.
+camp.m10.title = The Siege
+camp.m10.story = The Order is angry. Properly angry, with trumpets. Six waves will march against your halls. | The temple and the magic tower are ready - pray, pay and hold. If the core still glows after the sixth wave, they will need a new recruiting song.
+camp.m11.title = Patrol Paths
+camp.m11.story = This fortress runs like clockwork: four patrols march around the courtyard, and every corner has a tower looking at it. | Study their rounds, cut them off one by one, and when nothing in silver armour moves any more, the place is ours.
+camp.m12.title = Fire and Water
+camp.m12.story = Fire on one side, water on the other, and in between a fortress with a shard and a gate. The knights built it to show off. | Cross both rivers, destroy the gate of the order and take the shard. And mind which bridge you are standing on.
+camp.m13.title = The Treasure House of the Order
+camp.m13.story = The treasure house of the Order: thirteen thousand worth in the vaults - their whole retirement plan. | Claiming vaults makes noise, so the garrison will come running. Plan accordingly. Or do not, and enjoy the fireworks.
+camp.m14.title = The Ring of Towers
+camp.m14.story = Eight towers in a ring, upgraded to the very top. The commander here believes in walls and arrows the way imps believe in lunch. | Raze every single tower. Your creatures attack towers they can reach - send them with the flag and keep the healing spell handy.
+camp.m15.title = Beneath the Current
+camp.m15.story = No portal down here. No new recruits. Just what you brought, what I could hire, and a fortress across a cold, fast river. | Defeat every knight with the army you have. Every creature counts - keep them fed, paid and angry.
+camp.m16.title = Counterstrike
+camp.m16.story = Beyond the lava the gate of the order keeps sending waves, and it will not stop until the gate falls. | Hold your line, then push. Break the gate and their counterattack dies with it.
+camp.m17.title = The Bridge Town
+camp.m17.story = A whole town on bridges: three rivers, two keeps, two shards and plenty of treasure. Knights love bridges - they tear down yours and keep their own. | Take both shards and six thousand from their vaults.
+camp.m18.title = The Marshal's Lava Citadel
+camp.m18.story = Marshal Gerold the Unbending sits in his lava citadel, a paladin who has never bent anything - not his knee, not his opinion. | His gate guards the road to the Grand Master. Break it. Gerold will try to break you first.
+camp.m19.title = The Last Watch
+camp.m19.story = Three keeps hold the last shards before the citadel. The Order has thrown everything it has left into them, including its last good mood. | Take all three shards. After this, only one old man in shiny armour stands between you and your core.
+camp.m20.title = The Grand Master
+camp.m20.story = Grand Master Valerian Brightshield waits in his citadel beyond the great river, with the last shard and the gate of the order. He has prayed, polished and prepared for a hundred years. | Destroy his gate, take back the shard and make your core whole again. I will be right behind you. Well behind you.
+camp.epilogue = The last shard sinks into the core, and the darkness breathes again. Somewhere above, the Order of the Lightwatch is writing a very long report. | Crookfinger has made tea. You are whole, master. The underworld is yours.