Add share target, prompt templates, command palette and session organisation

- PWA share target: shared text/links start a new chat or go into a
  recent session (chooser dialog)
- Prompt templates (personal + global for admins) with {{placeholders}}
  that are asked for on insert; managed under Settings → Templates
- Ctrl/Cmd+K command palette; Alt+N new session, Alt+Up/Down switch
  sessions, Ctrl+, settings
- Sessions can be pinned, archived and filed into folders; the list can
  be grouped by date or by project, groups are collapsible
- Fix: the "What's new" dialog was never shown to signed-in users

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

web/src/whatsnew.ts

@@ -7,6 +7,8 @@ export const WHATS_NEW: Record<string, { en: string[]; de: string[] }> = {
       "Review loops per mode, project memory and personal memory",
       "Web terminal, git worktrees, accept changes hunk by hunk, voice input",
       "15 colour themes with light/dark/auto, push notifications on your phone",
+      "Ctrl+K command palette, prompt templates with placeholders, pin/archive sessions and sort them into folders",
+      "Share text and links from other apps to CodeCraft (installed app on Android)",
     ],
     de: [
       "Terminal-Client `codecraft`: lokal arbeiten wie mit Claude Code – Einstellungen → Konto → Terminal-Client",
@@ -14,6 +16,8 @@ export const WHATS_NEW: Record<string, { en: string[]; de: string[] }> = {
       "Review-Schleifen pro Modus, Projekt-Gedächtnis und persönliches Gedächtnis",
       "Web-Terminal, Git-Worktrees, Änderungen stückweise übernehmen, Spracheingabe",
       "15 Farbthemes mit Hell/Dunkel/Auto, Push-Benachrichtigungen aufs Handy",
+      "Ctrl+K-Befehlspalette, Prompt-Vorlagen mit Platzhaltern, Sessions anpinnen/archivieren und in Ordner sortieren",
+      "Texte und Links aus anderen Apps an CodeCraft teilen (installierte App unter Android)",
     ],
   },
 };