feat(terminal): refactor runtime and add mobile workspace (#2280)

Replace the legacy terminal flow with a shared authenticated WebSocket
runtime used across web, desktop, relay, and mobile surfaces.

- introduce the v3 terminal protocol with scoped attachments, snapshots,
  ordered output, bounded replay history, reconnects, and explicit lifecycle
- harden PTY creation, restart, resize, close, force-kill, idle cleanup,
  shell selection, login mode, environment sanitization, and appearance sync
- add runtime-aware terminal APIs with relay authentication and Electron parity
- add a fullscreen mobile terminal workspace with touch scrolling,
  long-press selection, safe-area controls, quick keys, and Ctrl/Alt input
- add terminal selection attachments, preview detection, project actions,
  shell settings, and localized UI
- harden Ghostty rendering, resize recovery, Unicode handling, block
  characters, line height, and stale-row behavior
- remove the obsolete terminal SSE path and update reverse-proxy guidance
- expand terminal runtime, transport, input, selection, and store coverage
- avoid duplicate web builds when preparing mobile assets in root CI builds

docs/REVERSE_PROXY.md

@@ -19,7 +19,6 @@ Use this guide when running OpenChamber behind Nginx, Nginx Proxy Manager, Caddy
   - `/api/global/event`
   - `/api/notifications/stream`
   - `/api/openchamber/events`
-  - `/api/terminal/:sessionId/stream`
 - Large request bodies for attachments and file operations
 - Long-lived read timeouts for live streams and terminal sessions
 
@@ -104,19 +103,6 @@ location ~ ^/api/(event|global/event|notifications/stream|openchamber/events)$ {
     proxy_send_timeout 3600s;
 }
 
-location ~ ^/api/terminal/.+/stream$ {
-    proxy_pass http://127.0.0.1:3000;
-    proxy_set_header Accept "text/event-stream";
-    proxy_set_header Cache-Control "no-cache";
-    proxy_buffering off;
-    proxy_cache off;
-    gzip off;
-    add_header X-Accel-Buffering "no" always;
-    add_header Cache-Control "no-cache, no-transform" always;
-    proxy_read_timeout 3600s;
-    proxy_send_timeout 3600s;
-}
-
 location /api {
     proxy_pass http://127.0.0.1:3000;
     proxy_read_timeout 3600s;
@@ -239,20 +225,6 @@ location = /api/openchamber/events {
     proxy_connect_timeout 30s;
 }
 
-location ~ ^/api/terminal/.+/stream$ {
-    proxy_pass http://127.0.0.1:3000;
-    proxy_set_header Accept "text/event-stream";
-    proxy_set_header Cache-Control "no-cache";
-    proxy_buffering off;
-    proxy_cache off;
-    gzip off;
-    add_header X-Accel-Buffering "no" always;
-    add_header Cache-Control "no-cache, no-transform" always;
-    proxy_read_timeout 3600s;
-    proxy_send_timeout 3600s;
-    proxy_connect_timeout 30s;
-}
-
 location /api {
     proxy_pass http://127.0.0.1:3000;
     proxy_read_timeout 3600s;