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

packages/web/README.md

@@ -108,6 +108,7 @@ OPENCODE_HOST=https://myhost:4096 OPENCODE_SKIP_START=true openchamber
 | `OPENCHAMBER_VERBOSE_REQUEST_LOGS` | Set to `true` to log every HTTP request; disabled by default to keep user logs small |
 | `OPENCHAMBER_SKIP_API_COMPRESSION` | Set to `true` to disable gzip compression for `/api/*` responses |
 | `OPENCHAMBER_COMPRESS_API` | Set to `true` to force `/api/*` compression, or `false` to disable it. Desktop runtime disables API compression by default to reduce local sidecar CPU use |
+| `OPENCHAMBER_TERMINAL_SHELL` | Preferred terminal shell executable used by the `Auto` setting before platform defaults |
 
 </details>