fix: improve Quick Prompt popup UX and settings design

- Fix window lifecycle: await renderer load before showing, debounce
  blur handler to prevent dropdown-induced dismiss
- Increase window height from 72px to 520px for response display
- Rewrite ModelSelector with tier-grouped upward-opening dropdown,
  reasoning effort controls, and Brain icon for reasoning models
- Rewrite QuickPromptInput with visible model trigger, animated
  chevron, auto-resize textarea, and proper stop button
- Improve QuickPromptResponse with compact thinking block, markdown
  code/pre/link styling, and refined spacing
- Polish QuickPromptActions with consistent sizing and hover states
- Redesign settings QuickPromptSettingsSection: replace flat radio
  list with compact grouped dropdown selector, only show reasoning
  effort when selected model supports it, combine hotkey toggle
  into single row
- Add markdown code block, inline code, and link CSS styles
- Fix dropdown animation direction for upward-opening selector
- Handle message-complete event in QuickPromptApp

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/index.ts

@@ -83,7 +83,7 @@ async function bootstrap(): Promise<void> {
       const hotkeySettings = workspace.settings.quickPrompt ?? createDefaultQuickPromptSettings();
       globalHotkeyService.register(hotkeySettings, () => {
         const win = ensureQuickPromptWindow();
-        if (win) toggleQuickPromptWindow(win);
+        if (win) void toggleQuickPromptWindow(win);
       });
 
       // Re-register hotkey when settings change