Knight fortresses: knight towers, patrols, alarm, claimable knight ground and vaults

- fortress.rs: fortress builder (masonry walls with doors, courtyard, corner towers, vault chambers
  full of mixed treasure, shard chamber, gate of the order as the heart, guards, patrols)
- Knight towers shoot the player's units; creatures tear down knight towers within reach
- Patrols walk their round; guards and patrols that spot an enemy alarm the others nearby
- Imps claim knight ground (slower, not next to fighting heroes); vaults hand over their treasure,
  shard chambers give the shard back; claiming alarms the knights
- Knights tear down the player's bridges near their posts
- Fix: units next to a tower could stop at the tile edge just out of melee reach
- Tests for towers, vault looting, patrols/alarm and bridge tearing

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

lang/de.lang

@@ -414,3 +414,12 @@ treasury.content = Enthält {0} in {1}
 hud.payday = Zahltag
 msg.payday_soon = Zahltag in {0} Sekunden: Deine Kreaturen wollen {1} Gold.
 hint.payday_short = Für den nächsten Zahltag reicht das Gold nicht. Unbezahlte Kreaturen werden wütend!
+
+# knight fortresses
+msg.enemy_tower_destroyed = Ein Ritter-{0} ist gefallen!
+msg.vault_taken = Ritterschatz erobert: Schätze im Wert von {0} gehören dir.
+msg.shard_taken = Ein Splitter deines Seelenkerns ist wieder in deiner Hand!
+msg.bridge_torn = Die Ritter haben eine deiner Brücken eingerissen!
+job.tear_bridge = Reißt eine Brücke ein
+job.patrol = Auf Patrouille
+job.guard = Hält Wache