Add worktrees, per-hunk review, effort per message, regenerate, voice input

- Isolated git worktree per session (create, status, merge, discard)
- Permission card: accept file-edit hunks individually; agent learns what was rejected
- Reasoning effort per message; regenerate the last answer with another model/effort
- Voice input via the Web Speech API
- Folder-up button in the file browser; ssh, rsync and mc in the image

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/components/Icon.tsx

@@ -193,6 +193,12 @@ const P: Record<string, ReactNode> = {
   ),
   dot: <circle cx="12" cy="12" r="4.5" className="fill" />,
   plus: <path d="M12 5v14M5 12h14" />,
+  mic: (
+    <>
+      <rect x="9" y="3" width="6" height="11" rx="3" />
+      <path d="M5.5 11a6.5 6.5 0 0 0 13 0M12 17.5V21M9 21h6" />
+    </>
+  ),
   clock: (
     <>
       <circle cx="12" cy="12" r="8.5" />