merge: integrate main into dev

Resolve 9 merge conflicts preserving both sides' intent:
- nix hash, bootstrap hostnames rename, websocket-server wiring
- session.ts handler dedup, snapshot fallback, worktree registration
- worktree-session git service + script/setup features
- sidebar-workspace-list setup navigation, session-context cleanup
- workspace-registry-bootstrap test kept (code still exists)
- checkout-git test additions from both sides

Post-merge fixes: isPaneFocused prop rename, server type rebuild.

packages/server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@getpaseo/server",
-  "version": "0.1.55-rc.2",
+  "version": "0.1.56",
   "description": "Paseo backend server",
   "type": "module",
   "publishConfig": {
@@ -60,8 +60,8 @@
     "@ai-sdk/openai": "2.0.52",
     "@anthropic-ai/claude-agent-sdk": "^0.2.11",
     "@deepgram/sdk": "^3.4.0",
-    "@getpaseo/highlight": "0.1.55-rc.2",
-    "@getpaseo/relay": "0.1.55-rc.2",
+    "@getpaseo/highlight": "0.1.56",
+    "@getpaseo/relay": "0.1.56",
     "@isaacs/ttlcache": "^2.1.4",
     "@modelcontextprotocol/sdk": "^1.20.1",
     "@opencode-ai/sdk": "1.2.6",