feat(fp): WP-22 — durable persistence (SQLite/EF Core)

Applications, documents (+ audit log) and the brief move off static in-memory
Dictionaries onto a real SQLite file via EF Core, so demo data survives a
process restart or `docker compose restart api` for the first time. The three
stores (ApplicationStore/DocumentStore/BriefStore) keep their exact public
signatures and static-class shape — no DI, no async ripple into Program.cs's
minimal-API handlers — each method just opens a short-lived AppDbContext via
Db.Create() under the same lock it already had. Opaque nested shapes (a
wizard's draft snapshot, a brief's sections/placeholders/status) are stored as
JSON text columns rather than redesigned into relational tables, matching the
existing "don't interpret it" posture.

Found two things the WP's own text got wrong, corrected in
docs/backlog/WP-22-durable-persistence.md's Deviations section: SeedData never
seeded these three stores (only the read-only BRP/DUO-mimicking GETs, which
stay in-memory) so there's no seed step; and no new docker-compose volume is
needed since the existing bind mount already covers the SQLite file — verified
against this environment's real podman-backed compose stack, not just by
reading the file.

Also: pinned SQLitePCLRaw.bundle_e_sqlite3 to 3.0.3 (EF Core Sqlite's own
transitive default bundles a pre-3.50.2 SQLite with a known high-severity
memory-corruption advisory); found and fixed a real xUnit test race where
concurrent test-class hosts stomped a shared static connection-string field,
fixed by disabling cross-class test parallelization rather than adding DI the
stores don't otherwise need.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -167,8 +167,9 @@ degrade to an instant navigation.
 - Styling: **CIBG Huisstijl** (customized Bootstrap 5.2) vendored in
   `public/cibg-huisstijl/`, loaded via `<link>`; `src/styles.scss` holds the
   `--rhc-*` → CIBG/`--bs-*` token bridge (ADR-0003). No styling npm dependency.
-- Data: ASP.NET Core backend (`backend/`, in-memory seeded) exposed via an OpenAPI
-  contract; the FE consumes an **NSwag-generated** typed client (`npm run gen:api`).
+- Data: ASP.NET Core backend (`backend/`, EF Core/SQLite-persisted; BRP/DUO
+  reference data stays in-memory-seeded) exposed via an OpenAPI contract; the FE
+  consumes an **NSwag-generated** typed client (`npm run gen:api`).
   The `?scenario=` toggle (`shared/infrastructure/scenario.interceptor.ts`) is
   **dev-only** — it is not wired into production builds.
 - `.npmrc` sets `legacy-peer-deps=true` because `@storybook/angular`'s peer range lags
@@ -194,9 +195,11 @@ We do **not** run `npm audit fix --force`: its proposed fix downgrades Angular 2
 
 ### Deliberately out of scope (POC)
 
-Real auth/DigiD, real BRP/DUO upstreams, a database/persisted audit store, NgRx,
-licensed RO/Rijks fonts + logo (system-font stack; text wordmark). (The backend
-itself _is_ implemented.) i18n's build seam is proven (see above) but
+Real auth/DigiD, real BRP/DUO upstreams, a production-grade database (Postgres/SQL
+Server — SQLite persists applications/documents/the brief + a real audit table,
+see `backend/README.md`, WP-22), NgRx, licensed RO/Rijks fonts + logo (system-font
+stack; text wordmark). (The backend itself _is_ implemented.) i18n's build seam is
+proven (see above) but
 production-quality translation, a runtime locale switcher, and RTL/pluralization
 edge cases are not — the `en` file is demo-quality, and locale is a build-time
 choice, not a switch in the running app.