Route downloads into Documents\Video / Documents\Audio and simplify the home page

- Create Documents\Video and Documents\Audio on startup (ensureMediaDirs), and
  route each download into them by kind when no explicit output folder is set.
  An empty outputDir now means "sort by type"; a chosen folder still overrides
  for both kinds.
- Settings/Onboarding "Download folder" gains a placeholder + hint describing
  the blank = route-by-type behaviour.
- Trim the home download bar to the essentials: URL box, Search and Paste
  buttons, format/quality, and the Download button. Removed the private-mode
  toggle, per-download Options panel, custom-command panel, command preview, and
  the saving-to-folder line.
- Bump version to 0.3.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main/index.ts

@@ -13,7 +13,7 @@ import {
 import { getYtdlpVersion, updateYtdlp } from './ytdlp'
 import { probeMedia } from './probe'
 import { startDownload, cancelDownload, previewCommand } from './download'
-import { getSettings, setSettings } from './settings'
+import { getSettings, setSettings, ensureMediaDirs } from './settings'
 import { listHistory, addHistory, removeHistory, removeManyHistory, clearHistory } from './history'
 import { listTemplates, saveTemplate, removeTemplate } from './templates'
 import { setupPortableData } from './portable'
@@ -303,6 +303,10 @@ if (isPrimaryInstance) {
   app.whenReady().then(() => {
     electronApp.setAppUserModelId('com.aerofetch.app')
 
+    // Create the default Documents\Video and Documents\Audio destinations so they
+    // exist from first launch (downloads are routed into them by kind).
+    ensureMediaDirs()
+
     app.on('browser-window-created', (_, window) => {
       optimizer.watchWindowShortcuts(window)
     })