[AZ-455] Decompose Step 3 — test task specs (AZ-457..AZ-482)

Adds 26 blackbox-test task specs under epic AZ-455 plus the matching
rows in _dependencies_table.md. Each task depends on AZ-456 (test
infrastructure). Advances autodev existing-code flow Step 5 → Step 6
(Implement Tests, cycle 1) ready for batch implementation.

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

_docs/02_tasks/todo/AZ-465_test_i18n.md

@@ -0,0 +1,66 @@
+# Test — i18n Coverage & Persistence
+
+**Task**: AZ-465_test_i18n
+**Name**: i18n key parity + t() coverage + detector + persistence
+**Description**: Implement the 4 blackbox tests that pin the i18n contract: en↔ua key parity (static), `t()` coverage (no raw user-visible strings), boot-time language detector, and persistence across reload.
+**Complexity**: 3 points
+**Dependencies**: AZ-456_test_infrastructure
+**Component**: 03_shared-ui + 10_app-shell (i18n) (Blackbox Tests)
+**Tracker**: AZ-465
+**Epic**: AZ-455
+
+## Problem
+
+A missing translation key or a hardcoded user-visible string only surfaces when a user switches language — by which point it's a customer-visible defect. Static checks + a behavioral test for detect/persist catch these at commit time.
+
+## Outcome
+
+- 4 scenarios pass per the contract.
+- The "no raw strings" check is enforceable in CI and produces a clear allow-list mechanism for legitimate non-i18n text (e.g. brand names).
+
+## Scope
+
+### Included
+
+| Scenario | Profile | Source file | results_report row |
+|----------|---------|-------------|--------------------|
+| FT-P-22 — i18n key parity en ↔ ua | static | blackbox-tests.md | 45 |
+| FT-P-23 — no raw user-visible strings outside `t(...)` | static | blackbox-tests.md | 46 |
+| FT-P-24 — i18n detector path used at first boot | fast + e2e | blackbox-tests.md | 47 |
+| FT-P-25 — i18n persistence across reload | fast + e2e | blackbox-tests.md | 48 |
+
+### Excluded
+
+- Adding a third language (project is en + ua per scope).
+- RTL support (not required by any AC).
+
+## Acceptance Criteria
+
+**AC-1: Key parity**
+Static check: `keys(en.json) == keys(ua.json)` (set equality). Test FAILS on any drift.
+
+**AC-2: t() coverage**
+Static check via ripgrep + AST walker: every JSX text node and string-literal `aria-*` / `title` / `placeholder` either lives in an i18n key, is in the allow-list (brand names, version strings), or fails the check.
+
+**AC-3: Detector path**
+First boot with no persisted language preference: SPA reads `navigator.language` and renders the matching bundle.
+
+**AC-4: Persistence**
+After user switches to UA and reloads, the UA bundle is rendered without explicit user action.
+
+## System Under Test Boundary
+
+- System under test: `src/i18n/i18n.ts` + every React component rendering user-visible text.
+- Allowed stubs: none beyond the standard test renderer.
+- Disallowed: reading the i18n state directly — the test asserts the rendered DOM text.
+- Expected observables per rows 45-48.
+
+## Constraints
+
+- Allow-list file lives at `tests/i18n-allowlist.json`; CI enforces it must not grow without a code-review reason.
+
+## Risks & Mitigation
+
+**Risk 1 — AST walker false positives**
+- *Risk*: the t() coverage walker may misclassify dynamic strings (e.g. `t(\`key_${id}\`)`) or ternaries.
+- *Mitigation*: explicit allow-list per file, plus a comment marker `// i18n-ok: <reason>` honored by the walker.