feat(collab): live collaboration — relay client, IPC bridge, self-hosting settings

[andrewchumchal]

Summary

Wires the desktop shell (Electron main process) to the live collaboration relay server introduced in OpenConduit/relay-server.

Changes

packages/desktop/src/main/collaboration/ (new)

• client.ts — WebSocket relay client: create, join, leave, send, lock request/release, streaming event forwarding. All URLs resolved dynamically from settings at call time (falls back to https://share.openconduit.ai).
• types.ts — Shared types for the collaboration IPC channel.

packages/desktop/src/main/ipc.ts

• Added collab:* IPC handlers: create, join, leave, send, lockRequest, lockRelease, onEvent, onInvite.
• SHARE_BASE is now dynamic — reads selfHosting.shareServerUrl from electron-store on each call so self-hosters don't need to restart.

packages/desktop/src/main/store/settings.ts

• Added selfHosting block to AppSettings: shareServerUrl (optional string).

packages/desktop/src/preload.ts + src/renderer/env.d.ts

• Exposed window.api.collab with full TypeScript types for all collab IPC channels.

packages/desktop/src/main.ts

• Registers the openconduit://join?roomId=… deep-link protocol handler; forwards invite events to the renderer via collab:invite.

Depends on

• Core UI: OpenConduit/core#88 (feat/live-collab) — CollaborationBar, StatusBar, useCollaboration, self-hosting settings UI.
• Relay server: OpenConduit/relay-server — deployable via Docker or self-hosted.