feat: migrate to OpenCode SDK worktrees with per-project config

Add SDK-based worktree management that lists and starts SDK worktrees
Migrate per-project setup to ~/.config/openchamber/<projectId>.json
Deprecate .openchamber legacy paths and adapt UI to new config

packages/ui/package.json

@@ -39,7 +39,7 @@
     "@fontsource/ibm-plex-sans": "^5.1.1",
     "@ibm/plex": "^6.4.1",
     "@lezer/highlight": "^1.2.3",
-    "@opencode-ai/sdk": "^1.1.34",
+    "@opencode-ai/sdk": "^1.1.36",
     "@pierre/diffs": "^1.0.5",
     "@radix-ui/react-collapsible": "^1.1.12",
     "@radix-ui/react-dialog": "^1.1.15",