feat(model): wählbares LLM-Modell pro User & pro Job

Mac-Worker:
- /api/summarize, /api/protocol, /api/preload akzeptieren optionales
  model-Feld → überschreibt den .env-Default pro Call, kein Restart nötig
- /api/models listet die lokal verfügbaren Ollama-Modelle + Default

LXC:
- User.default_model + Job.model (Migration für SQLite)
- /api/auth/me liefert default_model, PATCH speichert ihn sofort
- /api/mac/models proxiet die Liste an die UI
- Pipeline reicht job.model an Mac-Worker durch; leer = Worker-Default
- create_job & reprocess akzeptieren model-Override
- Snapshot-Meta nutzt job.model (genauer als /health-Snapshot)

UI:
- Header-Dropdown "Modell:" neben "Profil:" — sofort-speichert User-Default
- Jeder Job zeigt sein Modell als Tag (lila); leer bedeutet Worker-Default
- Reprocess öffnet einen Modal-Picker (statt simplem confirm), Auswahl
  aller verfügbaren Modelle inkl. "Worker-Default"

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lxc-frontend/app/core/mac_client.py

@@ -86,6 +86,13 @@ class MacClient:
             r.raise_for_status()
             return r.json().get("profiles", [])
 
+    async def list_models(self) -> dict:
+        """Liefert {models: [...], default: <worker .env default>}."""
+        async with httpx.AsyncClient(timeout=10) as c:
+            r = await c.get(f"{self.base_url}/api/models")
+            r.raise_for_status()
+            return r.json()
+
     async def fetch_log(self, job_id: int, last: int = 200) -> list[str]:
         """Holt die letzten Mac-Worker-Logzeilen für einen Job (für die Diagnose-Anzeige)."""
         try:
@@ -97,11 +104,12 @@ class MacClient:
             log.warning("fetch_log job=%s failed: %s", job_id, e)
             return []
 
-    async def preload(self, profile: str | None = None, job_id: int | None = None) -> dict:
+    async def preload(self, profile: str | None = None, model: str | None = None,
+                      job_id: int | None = None) -> dict:
         """Vor-Heizen: Ollama soll das Modell laden, bevor der echte Call läuft."""
         return await self._post_json_retry(
             f"{self.base_url}/api/preload",
-            {"profile": profile},
+            {"profile": profile, "model": model},
             job_id,
         )
 
@@ -122,18 +130,19 @@ class MacClient:
             return r.json()
 
     async def summarize(self, transcript: str, title: str = "", profile: str | None = None,
-                        job_id: int | None = None) -> dict:
+                        model: str | None = None, job_id: int | None = None) -> dict:
         return await self._post_json_retry(
             f"{self.base_url}/api/summarize",
-            {"transcript": transcript, "title": title, "profile": profile},
+            {"transcript": transcript, "title": title, "profile": profile, "model": model},
             job_id,
         )
 
     async def protocol(self, transcript: str, summary: dict, title: str = "", profile: str | None = None,
-                       job_id: int | None = None) -> dict:
+                       model: str | None = None, job_id: int | None = None) -> dict:
         return await self._post_json_retry(
             f"{self.base_url}/api/protocol",
-            {"transcript": transcript, "summary": summary, "title": title, "profile": profile},
+            {"transcript": transcript, "summary": summary, "title": title, "profile": profile,
+             "model": model},
             job_id,
         )
 

lxc-frontend/app/core/migrate.py

@@ -55,6 +55,16 @@ def run_migrations() -> None:
             log.info("Migration: füge job.last_heartbeat_at hinzu")
             conn.execute(text("ALTER TABLE job ADD COLUMN last_heartbeat_at DATETIME"))
 
+        # 6) Modell-Auswahl: user.default_model + job.model
+        user_cols = _existing_columns(conn, "user")
+        if user_cols and "default_model" not in user_cols:
+            log.info("Migration: füge user.default_model hinzu (leer = Worker-Default)")
+            conn.execute(text("ALTER TABLE user ADD COLUMN default_model VARCHAR DEFAULT ''"))
+        cols = _existing_columns(conn, "job")
+        if "model" not in cols:
+            log.info("Migration: füge job.model hinzu (leer = Worker-Default)")
+            conn.execute(text("ALTER TABLE job ADD COLUMN model VARCHAR DEFAULT ''"))
+
 
 def assign_orphan_jobs_to(user_id: int) -> int:
     """Weist alle Jobs ohne owner_id dem angegebenen User zu. Gibt Anzahl zurück."""