feat: massive chat reliability + UX pass (web/desktop/mobile/vscode) (#593)

## Added Features
- Add VS Code save-as-image flow for assistant messages via webview bridge + native save dialog.
- Add hourly desktop update checks after startup.
- Add new tool output display mode: `Changes` (auto-expand edit/write/patch only; keep activity expanded; mode guidance text).
- Add GitHub PR attachment flow in chat input with PR picker + attached PR chip/details.
- Add mobile overlay presentation for GitHub Issue and PR pickers (shared with desktop picker content).

## Fixes
- Save-gate project icon updates until explicit Save; allow icon removal with same save-gated behavior.
- Restore clickable chat action buttons in sticky header mode (desktop + Firefox hit-target issue).
- Clamp sticky user messages to bounded chat height and allow internal scrolling.
- Prevent drawer context crash during iPad/tablet orientation switching.
- Improve text-selection action menu placement on narrow screens.
- Move assistant message time into clock tooltip; keep duration display clean.
- Hide `Link GitHub Issue` row in VS Code chat input area (GitHub flow is not yet ready there).
- Remove laggy close animation in text-selection popover; keep open motion/positioning behavior.
- Fetch branches when picker opens and cache empty; show loading state instead of false “No branches found”.
- Fix share-image export metadata rendering (theme background resolution, timestamp rendering, footer alignment).
- Scope MCP services status/toggles to active directory to avoid cross-project leakage.
- Improve long user-message clamp behavior (40% cap variant, hidden scrollbar, scroll shadows, expansion detection).
- Fix desktop `Check for Updates` menu handler; prevent duplicate checks; show clear success/error toasts.
- Stabilize long user-message scrolling behavior (follow-up hardening).
- Avoid premature web update failure on slower servers.
- Restore user message image previews + fullscreen gallery navigation payload.
- Repair desktop chat drag-and-drop image attachments when native drop coords are missing.
- Move GitHub issue linking entry into Add attachment menu.
- Align header context usage percentage visuals with context panel.
- Align `@` file search with active project in all runtimes.
- Route `@` file discovery through OpenCode SDK `find.files`; remove legacy `/api/fs/search` reliance.
- Make chat `@` mention behavior consistent with files-style behavior.
- Keep status-row todos in stable order after status changes; add compact status icons; replace noisy priority labels.

## Refactors / UX Consistency
- Simplify chat attachment model and remove project file picker path.
- Keep composer focused on `@` mention file flow.
- Use direct `Attach files` action in VS Code instead of attachment dropdown path.
- Unify issue/PR picker behavior between desktop and mobile overlays.

packages/vscode/webview/main.tsx

@@ -452,24 +452,6 @@ const handleLocalApiRequest = async (url: URL, init?: RequestInit) => {
     return new Response(JSON.stringify(data), { status: 200, headers: { 'Content-Type': 'application/json' } });
   }
 
-  if (pathname.startsWith('/api/fs/search')) {
-    const directory = url.searchParams.get('directory') || '';
-    const query = url.searchParams.get('q') || '';
-    const limitParam = url.searchParams.get('limit');
-    const limit = limitParam ? Number(limitParam) : undefined;
-    const resolvedLimit = Number.isFinite(limit) ? limit : undefined;
-    const includeHidden = url.searchParams.get('includeHidden') === 'true';
-    const respectGitignore = url.searchParams.get('respectGitignore') !== 'false';
-    const data = await sendBridgeMessage('api:fs:search', {
-      directory,
-      query,
-      limit: resolvedLimit,
-      includeHidden,
-      respectGitignore,
-    });
-    return new Response(JSON.stringify(data), { status: 200, headers: { 'Content-Type': 'application/json' } });
-  }
-
   if (pathname.startsWith('/api/fs/mkdir')) {
     const body = init?.body ? JSON.parse(init.body as string) : {};
     const data = await sendBridgeMessage('api:fs:mkdir', { path: body.path });
@@ -495,6 +477,18 @@ const handleLocalApiRequest = async (url: URL, init?: RequestInit) => {
     return new Response(JSON.stringify(data), { status: 200, headers: { 'Content-Type': 'application/json' } });
   }
 
+  if (pathname.startsWith('/api/vscode/save-image') && method === 'POST') {
+    const body = init?.body ? JSON.parse(init.body as string) : {};
+    const fileName = typeof (body as { fileName?: unknown }).fileName === 'string'
+      ? (body as { fileName: string }).fileName
+      : undefined;
+    const dataUrl = typeof (body as { dataUrl?: unknown }).dataUrl === 'string'
+      ? (body as { dataUrl: string }).dataUrl
+      : undefined;
+    const data = await sendBridgeMessage('api:files/save-image', { fileName, dataUrl });
+    return new Response(JSON.stringify(data), { status: 200, headers: { 'Content-Type': 'application/json' } });
+  }
+
   if (pathname.startsWith('/api/config/agents/')) {
     const encodedName = pathname.slice('/api/config/agents/'.length);
     const name = decodeURIComponent(encodedName);