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/migrations/versions/011_add_indexes.py

@@ -0,0 +1,99 @@
+"""Add indexes on hot filter/FK-cascade columns, and user.is_active.
+
+Backend-perf audit (`scratchpad/audit/backend-perf.md` §4, M1): every
+migration to date created zero indexes; `EXPLAIN QUERY PLAN` against the full
+schema shows several hot paths doing a full table SCAN once the DB carries
+more than a handful of rows per table (multi-workspace deployment, years of
+FK-fetch history) — `planned_leave_day.count_by_parent_type` (2x per
+parent+child in analytics and plan/apply), `count_dubbeldagar`,
+`parental_leave_fetch.get_latest_by_parent`, and every FK-cascade column that
+`ON DELETE CASCADE` walks on a GDPR delete. These 14 indexes cover exactly
+those columns; see the audit for the full per-index rationale. Every
+`CREATE INDEX` below is mirrored verbatim (same columns, same order, no
+partial indexes) in `_FULL_SCHEMA` (`app/db/connection.py`) so
+`tests/integration/test_schema_parity.py` — which compares index sets between
+the Alembic chain and that hand-maintained DDL — stays green.
+
+Also adds `user.is_active` (default 1): `AuthService.login` and
+`get_user_from_token` already check `User.is_active` (account
+deactivation), but the column never existed — every account was
+unconditionally treated as active. This migration adds it and
+`SQLiteUserRepository` now reads/writes it.
+
+Revision ID: 011
+Revises: 010
+Create Date: 2026-09-18
+"""
+
+from __future__ import annotations
+
+from alembic import op
+
+revision: str = "011"
+down_revision: str | None = "010"
+branch_labels: str | None = None
+depends_on: str | None = None
+
+_UPGRADE_SQL = """
+ALTER TABLE "user" ADD COLUMN is_active INTEGER NOT NULL DEFAULT 1;
+CREATE INDEX idx_pld_parent_child_type_date
+    ON planned_leave_day (parent_personal_data_uuid, child_id, day_type, date);
+CREATE INDEX idx_pld_child_dubbeldag_date
+    ON planned_leave_day (child_id, is_dubbeldag, date);
+CREATE INDEX idx_pld_wish
+    ON planned_leave_day (wish_id);
+CREATE INDEX idx_plf_parent_child_fetched
+    ON parental_leave_fetch (personal_data_uuid, child_id, fetched_at);
+CREATE INDEX idx_plf_workspace
+    ON parental_leave_fetch (workspace_id);
+CREATE INDEX idx_plf_child
+    ON parental_leave_fetch (child_id);
+CREATE INDEX idx_leave_wish_workspace
+    ON leave_wish (workspace_id);
+CREATE INDEX idx_leave_wish_child
+    ON leave_wish (child_id);
+CREATE INDEX idx_leave_wish_parent
+    ON leave_wish (parent_personal_data_uuid);
+CREATE INDEX idx_child_workspace_birth
+    ON child (workspace_id, birth_date);
+CREATE INDEX idx_personal_data_workspace_deleted
+    ON personal_data (workspace_id, deleted_at);
+CREATE INDEX idx_invitation_workspace_status_created
+    ON workspace_invitation (workspace_id, status, created_at);
+CREATE INDEX idx_invitation_invited_by
+    ON workspace_invitation (invited_by_user_id);
+CREATE INDEX idx_vacation_days_workspace
+    ON vacation_days (workspace_id);
+"""
+
+_DOWNGRADE_SQL = """
+DROP INDEX idx_vacation_days_workspace;
+DROP INDEX idx_invitation_invited_by;
+DROP INDEX idx_invitation_workspace_status_created;
+DROP INDEX idx_personal_data_workspace_deleted;
+DROP INDEX idx_child_workspace_birth;
+DROP INDEX idx_leave_wish_parent;
+DROP INDEX idx_leave_wish_child;
+DROP INDEX idx_leave_wish_workspace;
+DROP INDEX idx_plf_child;
+DROP INDEX idx_plf_workspace;
+DROP INDEX idx_plf_parent_child_fetched;
+DROP INDEX idx_pld_wish;
+DROP INDEX idx_pld_child_dubbeldag_date;
+DROP INDEX idx_pld_parent_child_type_date;
+ALTER TABLE "user" DROP COLUMN is_active;
+"""
+
+
+def upgrade() -> None:
+    from sqlalchemy import text
+
+    for stmt in [s.strip() for s in _UPGRADE_SQL.split(";") if s.strip()]:
+        op.execute(text(stmt))
+
+
+def downgrade() -> None:
+    from sqlalchemy import text
+
+    for stmt in [s.strip() for s in _DOWNGRADE_SQL.split(";") if s.strip()]:
+        op.execute(text(stmt))