feat(M6): Weitere Hosts — MiniApps in Fenstern + AI-Agenten-Ausgabe-Bloecke (#364)

- Windows-Host: openMiniAppWindow-Helper + MiniAppWindowContent (windowStore);
  Oeffnen-Buttons im Chat-Block (MiniAppBlock) und Dashboard-Widget
- AI-Agenten-Host: Core-Tool send_miniapp (app/ai/miniapp_tools.py) —
  miniapp-Block in Agent-Chat (approval_request-Praezedenz), Permission
  fail-closed gegen aufrufenden User pro App; Registrierung im lifespan
- agent_loop: tool_context + agent_name (Raum-Aufloesung)
- Fix: MiniAppBlock nutzt useMiniapps (component-Feld) statt Legacy /comm/miniapps
- Tests: M6 7/7 (TDD rot->gruen), Backend-Regression 57/57, Vitest 26/26
  (4 neue Window-Tests), tsc clean, build OK

frontend/src/i18n/locales/de.json

@@ -163,7 +163,8 @@
       "taller": "Höher",
       "shorter": "Niedriger"
     },
-    "systemMetricsNoAccess": "Systemmetriken erfordern Admin-Rechte."
+    "systemMetricsNoAccess": "Systemmetriken erfordern Admin-Rechte.",
+    "openInWindow": "In Fenster öffnen"
   },
   "companies": {
     "title": "Firmen",

frontend/src/i18n/locales/en.json

@@ -163,7 +163,8 @@
       "taller": "Taller",
       "shorter": "Shorter"
     },
-    "systemMetricsNoAccess": "System metrics require admin rights."
+    "systemMetricsNoAccess": "System metrics require admin rights.",
+    "openInWindow": "Open in window"
   },
   "companies": {
     "title": "Companies",