docs+src: complete Steps 1-3 outcomes + auth re-sync baseline

This commit captures everything produced during autodev existing-code
Steps 1 (Document), 2 (Architecture Baseline Scan), and 3 (Test Spec),
together with the targeted auth + CORS re-sync triggered on 2026-05-14
when codebase drift was detected at Step 4 entry. None of this work was
previously committed.

Step 1 (Document) — 50+ _docs/02_document/ files: problem, solution,
architecture, system flows, glossary, module-layout, per-component
specs (01..06), modules, deployment, diagrams, data model, FINAL
report, verification log, discovery.

Step 2 (Architecture Baseline) — architecture_compliance_baseline.md.
Verdict PASS_WITH_WARNINGS (0 Critical, 0 High, 1 Medium, 2 Low). No
High/Critical findings; auto-chained to Step 3 per existing-code flow.

Step 3 (Test Spec) — _docs/02_document/tests/* (67 scenarios across
blackbox, security, resilience, resource-limit, performance), plus
e2e/docker-compose.test.yml, e2e/seed/run.sh, scripts/run-tests.sh,
scripts/run-performance-tests.sh. Coverage 88% over the active scope
(40 of 45 items covered, 6 RB-deferred, 5 documented-as-uncovered).

Targeted auth + CORS re-sync — replaces the deleted in-house token
issuer with a JWKS-verifier model. AuthController and TokenService
removed; JwtExtensions switched from HS256 symmetric to ES256 over
admin's JWKS. ConfigurationResolver and CorsConfigurationValidator
added under src/Infrastructure/. ADR-002 and ADR-006 retired; SEC-01,
SEC-02, SEC-03 marked Closed. One new testability risk recorded in
architecture.md Open Risks Section 6 (JWKS HTTPS gating).

Source changes:
- src/Auth/JwtExtensions.cs (modified) — ES256, JWKS, alg pinning
- src/Program.cs (modified) — DI wiring for ConfigurationResolver
  and CorsConfigurationValidator
- src/Controllers/AuthController.cs (deleted) — no in-service issuance
- src/Services/TokenService.cs (deleted) — same
- src/Infrastructure/ConfigurationResolver.cs (new)
- src/Infrastructure/CorsConfigurationValidator.cs (new)
- .env.example (new) — required env var documentation
- .gitignore (updated)

Cross-repo coordination: _docs/cross-repo/flights_h1_h2_h3_change_spec
captures the change-spec for downstream services that consumed the now
deleted /auth endpoints.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/02_document/modules/composition-program.md

@@ -0,0 +1,21 @@
+# Module: Composition (`Program.cs`)
+
+## Purpose
+
+Single **composition root**: configuration, PostgreSQL `AppDataConnection`, service registrations, **JWT**, **CORS**, Swagger, **migrator** on startup, **middleware** order, `MapControllers`, `/health`, `WebApplication.Run`.
+
+## Notable wiring
+
+- `DATABASE_URL` (required, no fallback — startup fails fast via `ConfigurationResolver.ResolveRequiredOrThrow`) → Npgsql connection string helper.
+- `JWT_ISSUER` / `JWT_AUDIENCE` / `JWT_JWKS_URL` for `AddJwtAuth` (all required; resolved by `ConfigurationResolver`). The validator pulls public ES256 keys from admin's JWKS endpoint; this service no longer holds an HMAC secret.
+- `CorsConfig:AllowedOrigins` / `CorsConfig:AllowAnyOrigin` for the default CORS policy; `CorsConfigurationValidator` refuses to start with a permissive policy in `Production`.
+- `RabbitMqConfig` from env + `AddHostedService<FailsafeProducer>()`.
+- Scoped services: `AnnotationService`, `MediaService`, `DatasetService`, `SettingsService`, `PathResolver`; singletons: `AnnotationEventService`, `RabbitMqConfig`.
+
+## Dependencies
+
+All modules; documented last after slices are understood.
+
+## Suite doc
+
+Operational/env story complements `01_annotations.md` deployment sections in suite architecture docs.