Harden the API and the data layer after a security and performance audit

Security
- Every route now requires a login and refuses ids outside the caller's
  workspace with 404: plan, leave-wishes, day-overrides and vacation-days
  were fully anonymous; every other router trusted client-supplied
  workspace/child/parent ids. Scraper sessions are bound to their owner.
- Invitations can no longer be created for a foreign workspace, and a
  redeemer who is already a member (or a full workspace) is refused.
- Production refuses the default JWT secret; API docs are hidden in
  production; a failed migration aborts startup instead of serving.
- Login and register no longer reveal whether an email exists; inactive
  accounts are rejected; /auth/refresh is rate limited.
- The FK scraper writes debug artefacts only when explicitly enabled,
  logs no scraped values or page text, clears the BankID QR as soon as it
  is scanned and purges finished sessions after five minutes.
- Real FK page captures are removed from the tree (history rewrite
  follows); the parser tests use a synthetic fixture.

Performance and correctness
- Plan apply/sync run inside one locked transaction with batched writes
  instead of one commit per row, so a failure mid-batch leaves nothing
  half-applied and concurrent syncs no longer corrupt each other.
- SQLite runs in WAL mode with a busy timeout; 14 indexes cover the
  filters that were full scans; argon2 hashing runs off the event loop;
  responses are gzipped.
- Frontend: a 401 now refreshes the token once and retries, so sessions
  no longer die silently after 15 minutes; every data hook discards
  stale responses; logout clears state even when the server call fails.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CsXCCcDfmV4Sps4ZQSvNEY

backend/app/main.py

@@ -14,6 +14,7 @@ from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from slowapi import _rate_limit_exceeded_handler
 from slowapi.errors import RateLimitExceeded
+from starlette.middleware.gzip import GZipMiddleware
 
 from app.config import settings
 from app.db.connection import connect, run_migrations
@@ -63,6 +64,7 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
             await asyncio.to_thread(run_migrations, f"sqlite:///{settings.sqlite_path}")
         except Exception as exc:
             logger.error("Migration failed — DB schema may be incomplete: %s", exc, exc_info=True)
+            raise
 
     # Re-enable after migrations: alembic's env.py calls fileConfig() which may
     # still touch logger state even with disable_existing_loggers=False.
@@ -78,7 +80,14 @@ async def lifespan(app: FastAPI) -> AsyncIterator[None]:
 
 
 def create_app() -> FastAPI:
-    app = FastAPI(title="Föräldraledigplannerare API", lifespan=lifespan)
+    is_production = settings.app_env == "production"
+    app = FastAPI(
+        title="Föräldraledigplannerare API",
+        lifespan=lifespan,
+        docs_url=None if is_production else "/docs",
+        redoc_url=None if is_production else "/redoc",
+        openapi_url=None if is_production else "/openapi.json",
+    )
 
     app.state.limiter = limiter
     app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
@@ -90,6 +99,8 @@ def create_app() -> FastAPI:
             logger.warning("%s %s %d", request.method, request.url.path, response.status_code)
         return response
 
+    app.add_middleware(GZipMiddleware, minimum_size=1024)
+
     app.add_middleware(
         CORSMiddleware,
         allow_origins=list(settings.cors_origins),