Add HAOS-Server sync for optional centralized management (Phase 5)

Enable the HAOS integration to optionally connect to the standalone
Immich Watcher server for config sync and event reporting.

Server-side:
- New /api/sync/* endpoints: GET trackers, POST template render,
  POST event report
- API key auth via X-API-Key header (accepts JWT access tokens)

Integration-side:
- New sync.py: ServerSyncClient with graceful error handling
  (all methods return defaults on connection failure)
- Options flow: optional server_url and server_api_key fields
  with connection validation
- Coordinator: fire-and-forget event reporting to server when
  album changes are detected
- Translations: en.json and ru.json updated with new fields

The connection is fully additive -- the integration works identically
without a server URL configured. Server failures never break HA.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/server/src/immich_watcher_server/api/sync.py

@@ -0,0 +1,172 @@
+"""Sync API endpoints for HAOS integration communication."""
+
+from fastapi import APIRouter, Depends, HTTPException, Header
+from pydantic import BaseModel
+from sqlmodel import select
+from sqlmodel.ext.asyncio.session import AsyncSession
+
+import jinja2
+
+from ..database.engine import get_session
+from ..database.models import (
+    AlbumTracker,
+    EventLog,
+    ImmichServer,
+    MessageTemplate,
+    NotificationTarget,
+    User,
+)
+
+router = APIRouter(prefix="/api/sync", tags=["sync"])
+
+
+async def _get_user_by_api_key(
+    x_api_key: str = Header(..., alias="X-API-Key"),
+    session: AsyncSession = Depends(get_session),
+) -> User:
+    """Authenticate via API key header (simpler than JWT for machine-to-machine).
+
+    The API key is the user's JWT access token or a dedicated sync token.
+    For simplicity, we accept the username:password base64 or look up by username.
+    In this implementation, we use the user ID embedded in the key.
+    """
+    # For now, accept a simple "user_id:secret" format or just validate JWT
+    from ..auth.jwt import decode_token
+    import jwt as pyjwt
+
+    try:
+        payload = decode_token(x_api_key)
+        user_id = int(payload["sub"])
+    except (pyjwt.PyJWTError, KeyError, ValueError) as exc:
+        raise HTTPException(status_code=401, detail="Invalid API key") from exc
+
+    user = await session.get(User, user_id)
+    if not user:
+        raise HTTPException(status_code=401, detail="User not found")
+    return user
+
+
+class SyncTrackerResponse(BaseModel):
+    id: int
+    name: str
+    server_url: str
+    server_api_key: str
+    album_ids: list[str]
+    event_types: list[str]
+    scan_interval: int
+    enabled: bool
+    template_body: str | None = None
+    targets: list[dict] = []
+
+
+class EventReport(BaseModel):
+    tracker_name: str
+    event_type: str
+    album_id: str
+    album_name: str
+    details: dict = {}
+
+
+class RenderRequest(BaseModel):
+    context: dict
+
+
+@router.get("/trackers", response_model=list[SyncTrackerResponse])
+async def get_sync_trackers(
+    user: User = Depends(_get_user_by_api_key),
+    session: AsyncSession = Depends(get_session),
+):
+    """Get all tracker configurations for syncing to HAOS integration."""
+    result = await session.exec(
+        select(AlbumTracker).where(AlbumTracker.user_id == user.id)
+    )
+    trackers = result.all()
+
+    responses = []
+    for tracker in trackers:
+        # Fetch server details
+        server = await session.get(ImmichServer, tracker.server_id)
+        if not server:
+            continue
+
+        # Fetch template body if assigned
+        template_body = None
+        if tracker.template_id:
+            template = await session.get(MessageTemplate, tracker.template_id)
+            if template:
+                template_body = template.body
+
+        # Fetch target configs
+        targets = []
+        for target_id in tracker.target_ids:
+            target = await session.get(NotificationTarget, target_id)
+            if target:
+                targets.append({
+                    "type": target.type,
+                    "name": target.name,
+                    "config": target.config,
+                })
+
+        responses.append(SyncTrackerResponse(
+            id=tracker.id,
+            name=tracker.name,
+            server_url=server.url,
+            server_api_key=server.api_key,
+            album_ids=tracker.album_ids,
+            event_types=tracker.event_types,
+            scan_interval=tracker.scan_interval,
+            enabled=tracker.enabled,
+            template_body=template_body,
+            targets=targets,
+        ))
+
+    return responses
+
+
+@router.post("/templates/{template_id}/render")
+async def render_template(
+    template_id: int,
+    body: RenderRequest,
+    user: User = Depends(_get_user_by_api_key),
+    session: AsyncSession = Depends(get_session),
+):
+    """Render a template with provided context (for HA to use server-managed templates)."""
+    template = await session.get(MessageTemplate, template_id)
+    if not template or template.user_id != user.id:
+        raise HTTPException(status_code=404, detail="Template not found")
+
+    try:
+        env = jinja2.Environment(autoescape=False)
+        tmpl = env.from_string(template.body)
+        rendered = tmpl.render(**body.context)
+        return {"rendered": rendered}
+    except jinja2.TemplateError as e:
+        raise HTTPException(status_code=400, detail=f"Template error: {e}")
+
+
+@router.post("/events")
+async def report_event(
+    body: EventReport,
+    user: User = Depends(_get_user_by_api_key),
+    session: AsyncSession = Depends(get_session),
+):
+    """Report an event from HAOS integration to the server for logging."""
+    # Find tracker by name (best-effort match)
+    result = await session.exec(
+        select(AlbumTracker).where(
+            AlbumTracker.user_id == user.id,
+            AlbumTracker.name == body.tracker_name,
+        )
+    )
+    tracker = result.first()
+
+    event = EventLog(
+        tracker_id=tracker.id if tracker else 0,
+        event_type=body.event_type,
+        album_id=body.album_id,
+        album_name=body.album_name,
+        details={**body.details, "source": "haos"},
+    )
+    session.add(event)
+    await session.commit()
+    return {"logged": True}