merge: resolve v1.23.0 upstream conflicts, preserve custom git provider config

Resolved conflicts in 8 files by taking upstream refactored code:
- desktop.ts: re-export DesktopSettings from registry
- openchamberConfig.ts: simplified project setup client
- persistence.ts: registry-derived settings, add git provider hydration
- search.ts: upstream search entries + git provider entries
- useConfigStore.ts: loadDesktopSettings() path
- settings-helpers.js: add gitProviderId/gitModelId/gitProviders sanitization
- DOCUMENTATION.md: upstream walkthrough docs
- vite.config.ts: upstream SW glob patterns

Custom fork additions preserved:
- gitProviderId, gitModelId, gitProviders fields in settings registry
- Git provider domain store hydration in persistence.ts
- Git provider search entries in search.ts
- Git provider sanitization in settings-helpers.js

packages/vscode/webview/main.tsx

@@ -398,6 +398,27 @@ const handleLocalApiRequest = async (input: RequestInfo | URL, url: URL, init: R
     return unsupportedWebRouteResponse('Scheduled tasks');
   }
 
+  // Project setup (worktree setup commands, project actions, draft starters)
+  // lives in the user's OpenChamber config dir; the extension host owns the
+  // file the way the OpenChamber server does elsewhere.
+  const projectSetupMatch = normalizedPathname.match(/^\/api\/projects\/([^/]+)\/config(\/shared)?$/);
+  if (projectSetupMatch && (method === 'GET' || method === 'PUT') && !(method === 'GET' && projectSetupMatch[2])) {
+    const projectId = decodeURIComponent(projectSetupMatch[1]);
+    const payload = method === 'GET'
+      ? { projectId }
+      : { projectId, patch: await extractJsonBody(input, init, method) };
+    const bridgeType = method === 'GET'
+      ? 'api:project-setup:get'
+      : projectSetupMatch[2] ? 'api:project-setup:update-shared' : 'api:project-setup:update';
+    try {
+      const data = await sendBridgeMessage(bridgeType, payload);
+      return jsonResponse(data, 200);
+    } catch (error) {
+      const message = error instanceof Error ? error.message : 'Project config request failed';
+      return jsonResponse({ error: message }, /must be|is required|unsupported characters/.test(message) ? 400 : 500);
+    }
+  }
+
   if (normalizedPathname === '/api/fs/git-dirs') {
     return unsupportedWebRouteResponse('Nested git repository discovery');
   }