docs: update documentation to OKF v0.1 format

docs/index.md

@@ -11,7 +11,7 @@ scoreboard, an event window with a public countdown, theming, and admin
 controls.
 
 The docs below are organized by purpose so agents can pull just the slice
-they need. Last regenerated 2026-07-22T22:17:11Z.
+they need. Last regenerated 2026-07-23T00:10:00Z.
 
 # Architecture
 
@@ -50,6 +50,9 @@ they need. Last regenerated 2026-07-22T22:17:11Z.
 * [Admin Endpoints](/api/admin.md) - Admin-only endpoints covering user
   management, general settings (`/api/v1/admin/general/*`), and
   categories (`/api/v1/admin/categories/*`).
+* [Challenges Endpoints](/api/challenges.md) - Authenticated challenge board,
+  detail, flag submission, event-state snapshot, and the combined
+  `/api/v1/events` SSE stream.
 * [System Endpoints](/api/system.md) - Bootstrap, event status, public SSE
   streams, public event-window settings, and the authenticated
   `/events/status` SSE stream.
@@ -80,6 +83,9 @@ they need. Last regenerated 2026-07-22T22:17:11Z.
 * [Authenticated Shell](/guides/authenticated-shell.md) - The header, LED
   + countdown, quick-jump tabs, user menu, and SSE lifecycle that frame
   every signed-in page.
+* [Challenges Board](/guides/challenges-board.md) - How a signed-in
+  player navigates `/challenges`, opens the modal, submits a flag, and
+  watches live solve updates.
 * [Change Password](/guides/change-password.md) - How a signed-in user
   changes their own password, including every error branch and the
   refresh-token revocation behavior.
@@ -103,3 +109,6 @@ they need. Last regenerated 2026-07-22T22:17:11Z.
   truth for the shell status dot's color in each `EventState`.
 * [Scoreboard Stream](/guides/scoreboard-stream.md) - How live solves are
   broadcast to clients.
+* [Notifications](/guides/notifications.md) - The root notification
+  store + global HTTP error interceptor that translate backend error
+  codes and statuses into friendly user-facing messages.