feat: improve VS Code dev flow and stabilize sidebar/chat behavior (#754)

* fix: improve session sidebar tooltip and truncation behavior

- Keep new-draft tooltip anchored to its trigger button
- Fix minimal-mode worktree/group header text truncation
- Tune minimal-mode right padding to reduce early label clipping

* fix: render reasoning through markdown pipeline

- Use Streamdown rendering for reasoning in live chat mode
- Remove italic styling from reasoning text
- Render expanded reasoning content with MarkdownRenderer

* chore: remove legacy electron dependencies

- Removed unused Electron packages from root and UI manifests
- Deleted obsolete Electron context menu type declaration
- Regenerated lockfile after dependency cleanup

* fix: handle non-repository folders in git status API

- Prevent 500 errors when status is requested outside a valid Git repo
- Improve repository detection using `git rev-parse --git-dir`
- Reduce noisy server logs for expected non-repo status checks

* fix unloaded session chat layout flicker

* fix: reduce noisy TTS status polling

Cache and dedupe TTS status requests, and only check provider availability when the related voice features are enabled so disabled voice setups stay quiet.

* perf: throttle background PR git status refreshes

* fix: improve VS Code Explorer file drop mentions in chat

- Add Explorer context action to insert selected files as @mentions.
- Handle Explorer drag-and-drop to prefill @file mentions instead of attachments.
- Prevent duplicate plain-path text when dropping multiple files.

* fix: deduplicate recent sessions in VS Code sidebar

- Hide sessions from main list when already shown in recent
- Apply dedup only in VS Code runtime
- Keep session search behavior unchanged

* feat: add true HMR dev flow for VS Code extension

- Load VS Code webview from Vite dev server with React refresh preamble
- Add `vscode:dev` runner that starts watchers and opens Extension Development Host
- Update VS Code dev docs and scripts to use the new HMR startup flow

* feat: polish VS Code session sidebar and attachment UX

- Add resizable sessions sidebar in VS Code layout
- Tighten session list spacing and hover behavior in VS Code
- Remove bulk file/image attach success toasts while keeping error toasts

packages/vscode/webview/main.tsx

@@ -982,6 +982,27 @@ onCommand('addToContext', (payload) => {
   });
 });
 
+onCommand('addFileMentions', (payload) => {
+  const rawPaths = Array.isArray((payload as { paths?: unknown[] })?.paths)
+    ? (payload as { paths: unknown[] }).paths
+    : [];
+  const paths = rawPaths
+    .filter((entry): entry is string => typeof entry === 'string')
+    .map((entry) => entry.trim())
+    .filter((entry) => entry.length > 0);
+
+  if (paths.length === 0) {
+    return;
+  }
+
+  const mentionText = paths.map((relativePath) => `@${relativePath}`).join(' ');
+
+  import('@/stores/useSessionStore').then(({ useSessionStore }) => {
+    const store = useSessionStore.getState();
+    store.setPendingInputText(mentionText, 'append-inline');
+  });
+});
+
 // Listen for createSessionWithPrompt command from extension (Explain, Improve Code)
 onCommand('createSessionWithPrompt', (payload) => {
   const { prompt } = payload as { prompt: string };