templates: add multi-category filter (repeatable or CSV) to GET /api/templates/search; add has_keywords filter; add categories listing endpoint with counts; update docs; add tests

app/main.py

@@ -90,6 +90,7 @@ from app.api.flexible import router as flexible_router
 from app.api.support import router as support_router
 from app.api.settings import router as settings_router
 from app.api.mortality import router as mortality_router
+from app.api.pensions import router as pensions_router
 
 logger.info("Including API routers")
 app.include_router(auth_router, prefix="/api/auth", tags=["authentication"])
@@ -104,6 +105,7 @@ app.include_router(support_router, prefix="/api/support", tags=["support"])
 app.include_router(settings_router, prefix="/api/settings", tags=["settings"])
 app.include_router(flexible_router, prefix="/api")
 app.include_router(mortality_router, prefix="/api/mortality", tags=["mortality"])
+app.include_router(pensions_router, prefix="/api/pensions", tags=["pensions"])
 
 
 @app.get("/", response_class=HTMLResponse)