Let the browser client choose a remote editor (VSCodium, Zed, etc.), not just VS Code

[Ephraim-9]

Problem
When T3 Code is used from a plain browser, the Open menu only lists VS Code. The list of editors comes from window.desktopBridge.probeRemoteEditors, which only the desktop app has, so browsers fall back to ["vscode"]. Someone using the web client from a machine with VSCodium or Zed has no way to pick it.

Proposal
In a browser, list every editor in REMOTE_CAPABLE_EDITOR_IDS. A browser can't detect what's installed, so it shows them all and remembers the choice. VS Code stays the default so nothing shifts to Cursor. VSCodium would still need an SSH-remote extension such as open-remote-ssh.

Status
I have a small working change on a fork branch, for reference only and not a PR: https://github.com/Ephraim-9/t3code/tree/feat/browser-remote-editor-picker. remoteOpen.test.ts passes and tsc is clean. Lint and the browser tests weren't run, and it hasn't been tried against a real remote server in a browser.

Related: #27510 (the triage report with the source analysis), #8938 (added Zed to the remote picker in the desktop app).