Token-Budget Hard-Stop + Banner bei aufgebrauchtem Budget

- check_license() liefert jetzt unlimited_budget, credits_total, credits_used,
  read_only_reason. Bei nicht-unlimited UND credits_used >= credits_total wird
  status=budget_exceeded, read_only=True gesetzt.
- require_writable_license blockiert mit 403 + X-License-Status-Header je nach Reason.
- /api/auth/me liefert read_only_reason und unlimited_budget; credits_percent_used
  wird nicht mehr auf 100 gekappt (echte Prozente).
- Frontend: Banner-Text dynamisch je nach reason (budget_exceeded/expired/...).
  Refresh-Button bei read_only deaktiviert + Tooltip. Globaler 403-Handler in
  api.js: bei X-License-Status -> Banner + Toast aktualisieren.

src/routers/auth.py

@@ -187,10 +187,11 @@ async def get_me(
         from services.license_service import check_license
         license_info = await check_license(db, current_user["tenant_id"])
 
-    # Credits-Daten laden
+    # Credits-Daten laden (echte Prozente, nicht gekappt)
     credits_total = None
     credits_remaining = None
     credits_percent_used = None
+    unlimited_budget = bool(license_info.get("unlimited_budget", False))
     if current_user.get("tenant_id"):
         lic_cursor = await db.execute(
             "SELECT credits_total, credits_used, cost_per_credit FROM licenses WHERE organization_id = ? AND status = 'active' ORDER BY id DESC LIMIT 1",
@@ -200,7 +201,7 @@ async def get_me(
             credits_total = lic_row["credits_total"]
             credits_used = lic_row["credits_used"] or 0
             credits_remaining = max(0, int(credits_total - credits_used))
-            credits_percent_used = round(min(100, (credits_used / credits_total) * 100), 1) if credits_total > 0 else 0
+            credits_percent_used = round((credits_used / credits_total) * 100, 1) if credits_total > 0 else 0
 
     return UserMeResponse(
         id=current_user["id"],
@@ -216,6 +217,8 @@ async def get_me(
         license_status=license_info.get("status", "unknown"),
         license_type=license_info.get("license_type", ""),
         read_only=license_info.get("read_only", False),
+        read_only_reason=license_info.get("read_only_reason"),
+        unlimited_budget=unlimited_budget,
         is_global_admin=current_user.get("is_global_admin", False),
     )