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/src/bridge.ts

@@ -1794,6 +1794,42 @@ export async function handleBridgeMessage(message: BridgeRequest, ctx?: BridgeCo
         return { id, type, success: true, data: { files, skipped } };
       }
 
+      case 'api:files/save-image': {
+        const rawFileName = (payload as { fileName?: unknown })?.fileName;
+        const rawDataUrl = (payload as { dataUrl?: unknown })?.dataUrl;
+        const dataUrl = typeof rawDataUrl === 'string' ? rawDataUrl.trim() : '';
+        if (!dataUrl.startsWith('data:image/')) {
+          return { id, type, success: false, error: 'Invalid image payload' };
+        }
+
+        const defaultFileName = typeof rawFileName === 'string' && rawFileName.trim().length > 0
+          ? rawFileName.trim()
+          : `message-${Date.now()}.png`;
+
+        const saveUri = await vscode.window.showSaveDialog({
+          saveLabel: 'Save image',
+          defaultUri: vscode.workspace.workspaceFolders?.[0]
+            ? vscode.Uri.joinPath(vscode.workspace.workspaceFolders[0].uri, defaultFileName)
+            : undefined,
+          filters: { Images: ['png'] },
+        });
+
+        if (!saveUri) {
+          return { id, type, success: true, data: { saved: false, canceled: true } };
+        }
+
+        const commaIndex = dataUrl.indexOf(',');
+        if (commaIndex === -1) {
+          return { id, type, success: false, error: 'Invalid image data URL' };
+        }
+
+        const base64 = dataUrl.slice(commaIndex + 1);
+        const bytes = Buffer.from(base64, 'base64');
+        await vscode.workspace.fs.writeFile(saveUri, bytes);
+
+        return { id, type, success: true, data: { saved: true, path: saveUri.fsPath || saveUri.toString() } };
+      }
+
       case 'api:config/settings:get': {
         const settings = readSettings(ctx);
         return { id, type, success: true, data: settings };