feat(backend): add deprecation middleware and API versioning support

- Add deprecation middleware for warning headers on sunset endpoints
- Add jails_v2 router for API v2 migration path
- Update CI workflow with new test coverage
- Update API versioning documentation
- Remove completed tasks from Tasks.md

backend/app/main.py

@@ -48,6 +48,7 @@ from app.exceptions import (
 )
 from app.middleware.correlation import CorrelationIdMiddleware
 from app.middleware.csrf import CsrfMiddleware
+from app.middleware.deprecation import DeprecationHeaderMiddleware
 from app.middleware.metrics import MetricsMiddleware
 from app.middleware.rate_limit import RateLimitMiddleware
 from app.models.response import ErrorResponse
@@ -62,6 +63,7 @@ from app.routers import (
     health,
     history,
     jails,
+    jails_v2,
     metrics,
     server,
     setup,
@@ -1074,6 +1076,7 @@ def create_app(settings: Settings | None = None) -> FastAPI:
     app.add_middleware(SetupRedirectMiddleware)
     app.add_middleware(MetricsMiddleware)
     app.add_middleware(CsrfMiddleware)
+    app.add_middleware(DeprecationHeaderMiddleware)
     app.add_middleware(
         RateLimitMiddleware,
         rate_limiter=app.state.global_rate_limiter,
@@ -1131,5 +1134,6 @@ def create_app(settings: Settings | None = None) -> FastAPI:
     app.include_router(server.router)
     app.include_router(history.router)
     app.include_router(blocklist.router)
+    app.include_router(jails_v2.router)
 
     return app