[AZ-447] autodev Steps 1-4 baseline: docs, tests, refactor specs

Captures the full output of autodev existing-code Phase A through
Step 4 (Code Testability Revision) for the Azaion UI workspace:

- Step 1 Document: _docs/02_document/ (FINAL_report, architecture,
  glossary, components/, modules/, diagrams/, system-flows,
  module-layout) plus _docs/00_problem/ + _docs/01_solution/ +
  _docs/legacy/ + _docs/how_to_test + README.
- Step 2 Architecture Baseline: architecture_compliance_baseline.md.
- Step 3 Test Spec: _docs/02_document/tests/ (environment,
  test-data, blackbox/performance/resilience/security/
  resource-limit tests, traceability-matrix), enum_spec_snapshot,
  expected_results/results_report.md (98 rows), plus the
  run-tests.sh + run-performance-tests.sh runners.
- Step 4 Code Testability Revision: 01-testability-refactoring/
  run dir (list-of-changes C01-C07, deferred_to_refactor,
  analysis/research_findings + refactoring_roadmap) and the 7
  child task specs AZ-448..AZ-454 under _docs/02_tasks/todo/
  plus _dependencies_table.md.
- _docs/_autodev_state.md pins the cursor at Step 4 / refactor
  Phase 4 entry so /autodev resumes cleanly.

Epic AZ-447 (UI testability gates) tracks the 7 child tasks that
will land in subsequent commits.

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

_docs/02_document/components/09_settings/description.md

@@ -0,0 +1,60 @@
+# 09 — Settings
+
+## 1. High-Level Overview
+
+**Purpose**: User-scoped + system settings: language, theme, system params, directory paths, aircraft default (duplicated with Admin).
+
+**Architectural Pattern**: Single-page feature, ~181 lines pre-consolidation.
+
+**Upstream dependencies**: `00_foundation`, `01_api-transport`, `03_shared-ui`.
+
+**Downstream consumers**: `10_app-shell` (routed at `/settings`).
+
+## 2. Internal Interfaces
+
+| Export | Notes |
+|--------|-------|
+| `SettingsPage()` | Top-level route component. Sub-sections: Personal (language, theme), System (params), Directories, Aircraft default. |
+
+## 3. External API Specification
+
+| Method | Path | Purpose |
+|--------|------|---------|
+| GET / PUT | `/api/annotations/settings/user` | Per-user UI preferences |
+| GET / PUT | `/api/admin/settings/system` | System params (saveSystem) |
+| GET / PUT | `/api/admin/settings/directories` | Storage paths (saveDirs) |
+| GET / PUT | `/api/admin/settings/aircraft-default` | Aircraft default (duplicated with Admin) |
+
+## 5. Implementation Details
+
+**State Management**: Page-local React state per form section.
+
+**Findings (B4, copied from state.json):**
+
+1. **`saveSystem` / `saveDirs` lack `try/finally`** — PUT failure leaves `saving:true` permanently and the spinner never stops. Step 4.
+2. **Numeric inputs use `parseInt(v) || 0`** — clearing a field silently writes 0. Step 4.
+3. **No optimistic concurrency** (no version field, no ETag) — Step 6 problem-extraction.
+4. **`handleToggleDefault` duplicated with AdminPage** — same global config behind two different pages. Surface intent in Step 6.
+5. **Possibly should be guarded by a permission like `SETTINGS`** — spec doesn't have such a code; server-enforces via 403. Less clear-cut than the `/admin` gap. Surface in Step 6.
+
+**Key Dependencies**: `react-i18next` (language switch).
+
+## 7. Caveats & Edge Cases
+
+- **Stuck-saving spinner** on PUT failure (#1).
+- **Silent zero on cleared numeric input** (#2) — corrupts settings.
+- **Aircraft default duplicated** with Admin — eventually one page should win.
+
+## 8. Dependency Graph
+
+**Must be implemented after**: `00_foundation`, `01_api-transport`, `03_shared-ui`.
+
+**Can be implemented in parallel with**: every other feature page.
+
+**Blocks**: `10_app-shell`.
+
+## Module Inventory
+
+| Path | Module Doc |
+|------|------------|
+| `src/features/settings/SettingsPage.tsx` | `_docs/02_document/modules/src__features__settings__SettingsPage.md` |