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_TODO.md

@@ -183,7 +183,7 @@ Features:
 
 ---
 
-### [ ] P4-3 · Knock-to-join Notifications for Admins
+### [x] P4-3 · Knock-to-join Notifications for Admins
 
 **Note:** The basic knock-to-join UX is covered in P1-11 (completed). This task adds the admin notification side.  
 **What:** Space/room admins see a notification badge when there are pending knock requests. A "Pending Join Requests" section in the members drawer or room settings. Approve (invite) or deny (kick) each knock.  
@@ -264,7 +264,7 @@ Themes:
 
 ---
 
-### [ ] P5-11 · AFK / Idle Auto-Mute in Voice
+### [x] P5-11 · AFK / Idle Auto-Mute in Voice
 
 **What:** Auto-mute mic after X minutes of silence (detected via Web Audio AnalyserNode). Show "You were auto-muted due to inactivity" toast with click-to-unmute. Admin-configurable via `io.lotus.afk_timeout` state event. Disableable in Settings → Calls.  
 **[AUDIT REQUIRED]** Verify auto-mute must go through the same CallControl bridge as manual mute.