fix: add USE_VIDEO permission to Member role and fix single-user video mode

Two fixes:
1. Member role (0x663) was missing USE_VIDEO (0x800) and SHARE_SCREEN (0x1000)
   bits, causing "permission denied" when non-owner users tried to enable camera.
   Migration 006 updates Member permissions to 0x1E63.
2. checkVideoMode() now checks voice.localCamera immediately instead of waiting
   for the server's voice_state broadcast, so video grid shows instantly when
   a single user enables their camera.

Client/tauri-client/src/pages/MainPage.ts

@@ -178,11 +178,13 @@ export function createMainPage(options: MainPageOptions): MountableComponent {
       if (isVideoMode) showChat();
       return;
     }
-    let anyCameraOn = false;
-    for (const user of channelUsers.values()) {
-      if (user.camera) {
-        anyCameraOn = true;
-        break;
+    let anyCameraOn = voice.localCamera; // Check local camera first (may not be in voiceUsers yet)
+    if (!anyCameraOn) {
+      for (const user of channelUsers.values()) {
+        if (user.camera) {
+          anyCameraOn = true;
+          break;
+        }
       }
     }
     if (anyCameraOn && !isVideoMode) {

Server/migrations/006_member_video_permissions.sql

@@ -0,0 +1,6 @@
+-- Migration 006: Add video and screenshare permissions to Member role
+-- Member was missing USE_VIDEO (0x800) and SHARE_SCREEN (0x1000).
+-- New value: 0x1E63 = SEND_MESSAGES | READ_MESSAGES | ATTACH_FILES |
+--                      ADD_REACTIONS | CONNECT_VOICE | SPEAK_VOICE |
+--                      USE_VIDEO | SHARE_SCREEN
+UPDATE roles SET permissions = 7779 WHERE id = 4 AND name = 'Member';