docs: document P4-3 (knock admin badge) and P5-11 (AFK auto-mute)

- LOTUS_FEATURES.md: added sections for Knock-to-Join Notifications for
  Admins and AFK Auto-Mute in Voice under their parent headings
- LOTUS_TODO.md: marked P4-3 and P5-11 as [x] completed
- README.md: updated Calls & Voice bullet list with AFK auto-mute entry;
  expanded knock admin badge entry with badge-count detail

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

LOTUS_FEATURES.md

@@ -232,6 +232,25 @@ Camera starts disabled on join. The `cameraOnJoin` setting is explicitly opt-in
 
 `M` key triggers `toggleSound()` in `CallControls.tsx`, toggling the deafen state without requiring a mouse click.
 
+### AFK Auto-Mute in Voice (P5-11)
+
+Automatically mutes the microphone after a configurable period of microphone-on silence.
+
+**Implementation:**
+
+- `useAfkAutoMute(callEmbed)` hook opens a separate monitoring-only `getUserMedia` stream (independent of Element Call's stream) and analyzes it via `AudioContext` + `AnalyserNode`
+- RMS level is sampled every 500ms; if it stays below threshold while the mic is on, the silence timer starts
+- After the configured timeout (`afkTimeoutMinutes` setting), `callEmbed.control.setMicrophone(false)` mutes the mic and an in-app toast is shown
+- Monitoring stream and `AudioContext` are fully cleaned up on unmount (no resource leak)
+- Activated inside `CallControls` via `useAfkAutoMute(callEmbed)` — no changes required to `CallEmbed` or Element Call
+
+**Settings (Settings → Calls):**
+
+- **AFK Auto-Mute** toggle (default: off)
+- **Idle Timeout** dropdown — 1 / 5 / 10 / 20 / 30 minutes (shown only when enabled; default: 10 minutes)
+
+Hook: `src/app/hooks/useAfkAutoMute.ts`
+
 ### Noise Suppression Toggle
 
 A `noiseSuppression` URL parameter is passed to the Element Call widget URL, allowing the noise suppression feature to be toggled from within Lotus settings.
@@ -624,6 +643,17 @@ A toggle in **Settings → Privacy** switches between sending `m.read` (public r
 - Clicking sends `mx.knockRoom(roomId)` with an optional reason
 - The members drawer shows a "Pending Requests" section for room admins, listing users who have knocked
 
+### Knock-to-Join Notifications for Admins (P4-3)
+
+Room and space admins are notified in real time when users knock on a restricted room.
+
+- `usePendingKnocks(room)` hook listens to `RoomMemberEvent.Membership` events and returns all members currently in the `knock` state
+- Power level check: only shown to users with sufficient invite-level permissions (`usePowerLevelsContext()`)
+- **Members button badge:** when knocks are pending, a `Warning`-variant solid `Badge` overlays the Members button in the room header showing the pending count
+- Badge is `aria-hidden`; the Members button `aria-label` is updated to announce the count for screen readers
+
+Hook: `src/app/hooks/usePendingKnocks.ts`
+
 ### Code Syntax Highlighting (TDS)
 
 `syntaxHighlight.ts` provides TDS-aware syntax highlighting using inline styles derived from `--lt-accent-*` CSS variables. Supported languages: JavaScript, TypeScript, JSX, TSX, Python, Rust. Falls back to ReactPrism for unsupported languages.