docs: update documentation to OKF v0.1 format

docs/architecture/key-files.md

@@ -3,7 +3,7 @@ type: architecture
 title: Key Files Index
 description: One-line responsibility for important source and contract-test files, including strict event-window validation, the public bootstrap SSE listener, the challenges full-replace import flow, the authenticated player-facing challenges board, and the per-user `solvedByMe` reset on the session boundary.
 tags: [architecture, key-files, event-window, validation, default-challenge-ip, sse, bootstrap, migrations, challenges, import, board, notifications, per-user, session]
-timestamp: 2026-07-23T03:45:00Z
+timestamp: 2026-07-23T04:05:00Z
 ---
 
 # Backend
@@ -77,7 +77,7 @@ timestamp: 2026-07-23T03:45:00Z
 | `frontend/src/app/features/challenges/challenges.service.ts` | HTTP service for `/api/v1/challenges/{board,status,:id,:id/solves}` returning typed `ApiErrorEnvelope`s. `getDetail` always requests `?include=solvers` so the modal can render the solvers list in one round-trip; `getBoard` only attaches `include=solvers` when the caller opts in. |
 | `frontend/src/app/features/challenges/challenges.pure.ts` | Pure types and helpers (`BoardCard`, `SolverRow`, `SolveEventPayload`, `parseSolveEvent`, `mergeSolveEventIntoSolvers`, `messageForSolveError`, `formatDdHhMm`). |
 | `frontend/src/app/features/challenges/category-column.component.ts` | Renders a single category column (header + cards) on the challenges board. |
-| `frontend/src/app/features/challenges/challenge-card.component.ts` | Renders a single challenge card on the board (difficulty, live points, solve count, `✓` when solved by the player). |
+| `frontend/src/app/features/challenges/challenge-card.component.ts` | Renders a single challenge card on the board as a semantic `<button>` (difficulty, live points, solve count, `✓` when solved by the player). Exposes `data-testid="challenge-card-<id>"`, `data-solved`, `aria-pressed`, an accessible name (`Challenge <name>, solved|not solved`), and an inner `data-testid="challenge-check-<id>"` for the solved glyph. |
 | `frontend/src/app/features/challenges/challenge-modal.component.ts` | Challenge detail modal: description, flag form, awarded banner, solvers list, live-solve updates. |
 | `frontend/src/app/core/services/notification.service.ts` | Root-provided signal-backed store of `{ id, kind, message, ts }` records; `error()` / `info()` push, `dismiss(id)` / `clear()` remove. |
 | `frontend/src/app/core/interceptors/error-notification.interceptor.ts` | Translates `HttpErrorResponse` into friendly messages and pushes them to `NotificationService` (with suppression for `/api/v1/auth/{login,csrf,register}` and `/api/v1/challenges/status`). |
@@ -86,6 +86,7 @@ timestamp: 2026-07-23T03:45:00Z
 | `tests/frontend/challenges.store.spec.ts` | Signal store: board mutation, live solve merge, listeners, `stop()`. The "marks solvedByMe" and "does not double-count" tests now call `setMyUserId('me-1')` *before* `load()` to exercise the realistic page-mount sequence. |
 | `tests/frontend/challenges.store.reset.spec.ts` | Per-user `solvedByMe` regression suite: `reset()` clears board/detail/myUserId/SSE; switching user id flushes the previous board; **orphan board** (cached with no recorded user id) is cleared when PlayerB's id is set; a non-mine solve never flips `solvedByMe` from `false` to `true`; `applySubmitResponse` takes the server value verbatim. |
 | `tests/frontend/notification-interceptor.spec.ts` | Interceptor suppression rules and friendly message mapping. |
+| `tests/frontend/challenge-card-accessibility.spec.ts` | Challenge-card accessibility contract: keyboard activation, `aria-pressed` toggling, accessible-name composition, and the `data-solved` / `challenge-check-*` test selectors. |
 | `tests/backend/challenges-board.spec.ts` | Board query shape, ordering, `?include=solvers`. |
 | `tests/backend/challenges-status-rest.spec.ts` | `/api/v1/challenges/status` snapshot shape. |
 | `tests/backend/challenges-events-sse.spec.ts` | `/api/v1/events` SSE: status + solve frames, dedup, ordering. |