feat: remove hardcoded command templates, enforce template system exclusively

- Remove ALL hardcoded EN/RU fallback strings from handler.py — every
  command response now renders through CommandTemplateSlot templates
- _render_cmd_template now returns error placeholder instead of None
  when template is missing, ensuring no silent failures
- Fix register_commands_with_telegram tuple unpacking bug (was ignoring
  cmd_template_slots from _resolve_command_context)
- Auto-assign system default template (matching locale) on command
  config creation when none specified
- Add command_template_config_id to CommandConfigCreate model
- Remove "no template" option from frontend dropdown — template is
  now required for command configs
- Auto-select first matching template when creating new command config
- Fix || vs ?? for command_template_config_id, default_count, and
  rate_limits in frontend edit function (0 was treated as falsy)

packages/server/src/notify_bridge_server/api/command_configs.py

@@ -10,7 +10,7 @@ from sqlmodel.ext.asyncio.session import AsyncSession
 
 from ..auth.dependencies import get_current_user
 from ..database.engine import get_session
-from ..database.models import CommandConfig, CommandTracker, User
+from ..database.models import CommandConfig, CommandTemplateConfig, CommandTracker, User
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -26,6 +26,7 @@ class CommandConfigCreate(BaseModel):
     response_mode: str = "media"
     default_count: int = 5
     rate_limits: dict[str, Any] = {}
+    command_template_config_id: int | None = None
 
 
 class CommandConfigUpdate(BaseModel):
@@ -36,6 +37,7 @@ class CommandConfigUpdate(BaseModel):
     response_mode: str | None = None
     default_count: int | None = None
     rate_limits: dict[str, Any] | None = None
+    command_template_config_id: int | None = None
 
 
 @router.get("")
@@ -65,7 +67,18 @@ async def create_command_config(
             detail=f"Invalid provider_type. Must be one of: {', '.join(valid_types)}",
         )
 
-    config = CommandConfig(user_id=user.id, **body.model_dump())
+    data = body.model_dump()
+    # Auto-assign system default template if none specified
+    if not data.get("command_template_config_id"):
+        locale = data.get("locale", "en")
+        provider_type = data.get("provider_type", "immich")
+        default_tpl = await _find_system_default_template(
+            session, provider_type, locale
+        )
+        if default_tpl:
+            data["command_template_config_id"] = default_tpl.id
+
+    config = CommandConfig(user_id=user.id, **data)
     session.add(config)
     await session.commit()
     await session.refresh(config)
@@ -91,9 +104,13 @@ async def update_command_config(
     session: AsyncSession = Depends(get_session),
 ):
     """Update a command config."""
+    from sqlalchemy.orm.attributes import flag_modified
     config = await _get_user_config(session, config_id, user.id)
     for field, value in body.model_dump(exclude_unset=True).items():
         setattr(config, field, value)
+        # JSON columns need explicit dirty flag for SQLAlchemy change detection
+        if field in ("rate_limits", "enabled_commands"):
+            flag_modified(config, field)
     session.add(config)
     await session.commit()
     await session.refresh(config)
@@ -129,6 +146,7 @@ def _config_response(c: CommandConfig) -> dict:
         "response_mode": c.response_mode,
         "default_count": c.default_count,
         "rate_limits": c.rate_limits or {},
+        "command_template_config_id": c.command_template_config_id,
         "created_at": c.created_at.isoformat(),
     }
 
@@ -140,3 +158,24 @@ async def _get_user_config(
     if not config or config.user_id != user_id:
         raise HTTPException(status_code=404, detail="Command config not found")
     return config
+
+
+async def _find_system_default_template(
+    session: AsyncSession, provider_type: str, locale: str
+) -> CommandTemplateConfig | None:
+    """Find a system default (user_id=0) command template matching provider + locale."""
+    # Try exact locale match first (e.g. "Default Commands (EN)" for locale "en")
+    locale_upper = locale.upper()
+    result = await session.exec(
+        select(CommandTemplateConfig).where(
+            CommandTemplateConfig.user_id == 0,
+            CommandTemplateConfig.provider_type == provider_type,
+        )
+    )
+    templates = result.all()
+    # Match by locale suffix in name, e.g. "(EN)" or "(RU)"
+    for tpl in templates:
+        if f"({locale_upper})" in tpl.name:
+            return tpl
+    # Fallback: return first system template for this provider
+    return templates[0] if templates else None