fix: activate plugins on startup + register routes + seed admin script

- lifespan: load active plugins from DB, call on_activate, register routes
- Fixes: Calendar/Mail/DMS/Tags/Permissions routes returning 404
- scripts/seed_admin.py: creates default tenant + admin user

app/main.py

@@ -11,8 +11,12 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse
 from fastapi.staticfiles import StaticFiles
 from starlette.middleware.base import BaseHTTPMiddleware
+import importlib
+import logging
 import os
 
+logger = logging.getLogger(__name__)
+
 from app.config import get_settings
 from app.core.db import close_engine, get_engine
 from app.core.middleware import CSRFMiddleware
@@ -91,6 +95,38 @@ async def lifespan(app: FastAPI):
     registry.initialize(get_engine(), app)
     registry.discover_builtins()
 
+    # Activate plugins that are marked active in the database
+    from sqlalchemy import select as sa_select
+    from sqlalchemy.ext.asyncio import async_sessionmaker
+    from app.models.plugin import Plugin as PluginModel
+    from app.core.event_bus import get_event_bus
+
+    event_bus = get_event_bus()
+    async_session = async_sessionmaker(get_engine(), expire_on_commit=False)
+
+    async with async_session() as db:
+        result = await db.execute(
+            sa_select(PluginModel).where(PluginModel.active == True)  # noqa: E712
+        )
+        active_plugins = result.scalars().all()
+
+        for plugin_record in active_plugins:
+            plugin = registry.get_plugin(plugin_record.name)
+            if plugin is None:
+                continue
+            try:
+                await plugin.on_activate(db, container, event_bus)
+                # Register plugin routes into FastAPI app
+                for route_def in plugin.manifest.routes:
+                    router_module = importlib.import_module(route_def.module)
+                    router = getattr(router_module, route_def.router_attr)
+                    app.include_router(router)
+                logger.info(f"Activated plugin: {plugin_record.name}")
+            except Exception as exc:
+                logger.warning(f"Failed to activate plugin {plugin_record.name}: {exc}")
+
+        await db.commit()
+
     yield
 
     await close_engine()