feat: backend read api for all entities (messages/groups/calls/sms/org/sync)

Adds the read-only API surface the upcoming Vue frontend needs to browse all
mirrored entities. Follows the existing customer-router pattern: Annotated
deps, Page[T] envelope, select+where+order_by, count() for total.

Endpoints (all GET):
* /api/departments          -> list[DepartmentOut] (path-ordered, plain list)
* /api/staff                -> Page[StaffOut] (department_id, is_on_job filters)
* /api/accounts             -> Page[AccountOut] (channel filter; unified
                             wechat+whatsapp projection built in memory)
* /api/messages             -> Page[MessageOut] (channel/owner/talker/room/
                             [start,end] filters; ordered timestamp asc)
* /api/groups               -> Page[GroupOut] (channel/owner filters)
* /api/groups/{id}/members  -> list[GroupMemberOut] (404 on unknown room)
* /api/calls                -> Page[PhoneCallOut] (channel/user/time window;
                             ordered start_call_time desc)
* /api/sms                  -> Page[SmsOut] (user/time window; create_time desc)
* /api/sync/status          -> {states, recent_runs} monitor payload

Schemas (Pydantic v2, from_attributes=True): MessageOut, GroupOut,
GroupMemberOut, PhoneCallOut, SmsOut, DepartmentOut, StaffOut, AccountOut
(unified across two tables), SyncStateOut, SyncRunOut, SyncStatusOut.
Only human-relevant fields per entity are exposed.

Tests: per-router TDD via httpx ASGITransport against an in-memory SQLite
override of get_session. A shared make_client factory in conftest.py builds
the seeded client, deduping the ~40-line fixture across the six new files.
41 new tests cover shape + every documented filter + pagination + ordering
(nulls-last verified on all desc/asc time columns).

Suite: 226 -> 267 passing. ruff check clean.

Co-Authored-By: Claude <noreply@anthropic.com>

yunke-server/app/api/main.py

@@ -8,6 +8,14 @@ Includes:
 * ``GET /api/health``  -> ``{"status": "ok"}`` liveness probe.
 * ``GET /api/customers`` (see :mod:`app.api.routers.customer`).
 * ``GET /api/media/{media_hash}`` (see :mod:`app.api.routers.media`).
+* ``GET /api/departments`` / ``/api/staff`` / ``/api/accounts``
+  (see :mod:`app.api.routers.organization`).
+* ``GET /api/messages`` (see :mod:`app.api.routers.messages`).
+* ``GET /api/groups`` / ``/api/groups/{room_id}/members``
+  (see :mod:`app.api.routers.groups`).
+* ``GET /api/calls`` (see :mod:`app.api.routers.calls`).
+* ``GET /api/sms`` (see :mod:`app.api.routers.sms`).
+* ``GET /api/sync/status`` (see :mod:`app.api.routers.sync`).
 
 CORS is configured permissively (wildcard origin, no credentials) so the local
 frontend can call the API during development.
@@ -26,7 +34,16 @@ from fastapi import Depends, FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from app.api.auth import require_auth
-from app.api.routers import customer, media
+from app.api.routers import (
+    calls,
+    customer,
+    groups,
+    media,
+    messages,
+    organization,
+    sms,
+    sync,
+)
 
 app = FastAPI(title="yunke data mirror", dependencies=[Depends(require_auth)])
 
@@ -39,6 +56,12 @@ app.add_middleware(
 
 app.include_router(customer.router)
 app.include_router(media.router)
+app.include_router(organization.router)
+app.include_router(messages.router)
+app.include_router(groups.router)
+app.include_router(calls.router)
+app.include_router(sms.router)
+app.include_router(sync.router)
 
 
 @app.get("/api/health")