Restore window layouts on app launch

[kordless]

Goal

On app startup, read all saved layouts from electron-store (windowLayouts key) and recreate each window with its saved tabs, panes, cwds, and active session.

Scope

• After app.on('ready') fires and the sidecar is up (app/index.ts:330), iterate windowLayouts entries
• For each entry: create a BrowserWindow at the saved position/size, wait for renderer load, then drive a sequence of RPC calls to recreate the layout
• Reuse the saved windowUid so the next save round-trips to the same slot

Restoration sequence per window

1. Open window with saved position/size
2. Wait for renderer ready
3. For each tab in saved layout:
   • Send RPC 'create tab' with saved tabName
   • For each pane in the tab's BSP tree (root → leaves):
     • If root: spawn shell with cwd from saved cwds[sessionUid]
     • If split: send RPC 'split pane' with parent UID, direction, sizes
     • If web pane: send RPC 'open web pane' with URL from saved webUrls[sessionUid]
4. Send RPC 'set active session' with saved activeSessionUid

Existing primitives

• app/ui/window.ts:189 createSession() already supports cwd option — pass through saved cwd
• bridge.ts:718 updateSessionLayout() flows BSP coords back; should round-trip cleanly
• Web pane creation already exists via /api/web-pane and renderer webUrl handling

New RPC handlers needed (renderer side)

• 'replay tab' — create a tab with given name + initial cwd
• 'replay split' — split a given pane in a given direction with given sizes
• 'replay web pane' — open a web pane in a given pane slot with given URL
• 'replay set active' — set the active session

These are thin wrappers around existing Redux actions (split, setActive, etc.).

Edge cases

• Saved cwd no longer exists → fall back to home directory (existing createSession already validates with existsSync)
• Saved layout references a window position off-screen → clamp via existing windowUtils.positionIsValid()
• Multiple saved windows → open them sequentially to avoid race conditions

Files touched

• app/index.ts — startup hook reads layouts and orchestrates restore
• lib/index.tsx or renderer entry — handle replay RPCs
• lib/actions/term-groups.ts — may need a replaySplit action that takes explicit sizes

Depends on

#82 (save layout) — without saved data there's nothing to restore