M5: Windows client moderation UI; add C ABI getters for account list, user mute/deafen, channel topic

clients/windows/README.md

@@ -65,6 +65,24 @@ On first connect to a new server:
 - The server identity dialog will appear. The TLS leaf-cert SHA-256 fingerprint is shown;
   accept to pin it. Subsequent connects to the same server will be silent (MATCHED).
 
+## M5 — Moderation & admin UI
+
+The WinForms client now exposes all M5 operations through the main menu and context menus:
+
+- **Admin → Server accounts…** — create, reset password, and delete server accounts
+  (requires `can_admin_accounts`).
+- **Channel tree right-click** — create, edit, and delete channels. The edit dialog exposes the
+  full per-channel Opus configuration: mono/stereo, sample rate, bitrate, frame size,
+  application mode, FEC, expected packet loss, DTX, and complexity.
+- **User list right-click** — move, kick, ban, server mute/deafen, and set permissions
+  (items are gated by your own permissions).
+- **Activity log** shows async `GenericResult` feedback for every moderation request.
+- **User list** shows text indicators for self-mute, self-deafen, server-mute, and
+  server-deafen states.
+
+These operations require an admin-provisioned account with the appropriate permissions; the
+connect dialog already supports username/password auth.
+
 ## Known limitations
 
 - **PTT is focus-scoped** — the push-to-talk key only works while the VoiceCat window has
@@ -72,8 +90,6 @@ On first connect to a new server:
 - **Receive-side noise reduction** checkbox in per-user tuning is wired end-to-end but is a
   passthrough no-op until a real APM/NS backend is built (no working Windows/MSVC port of
   `webrtc-audio-processing` upstream — see `docs/tech-stack.md §1`).
-- **Admin/moderation UI** is not present — kick/ban/permissions/account provisioning are M5
-  scope (requires server-side dispatch first).
 - **TOFU pins the TLS leaf cert**, not the declared Ed25519 identity fingerprint. Both are
   shown in the identity dialog, but the cert fingerprint is the value that is actually
   verified on reconnect. See `docs/security.md §1.1`.