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/Files.tsx

@@ -268,6 +268,15 @@ export function Files({ onMenu }: { onMenu: () => void }) {
         </button>
       </div>
       <div className="crumbs">
+        <button
+          className="small ghost crumbs-up"
+          disabled={!listing?.parent}
+          onClick={() => listing?.parent && void confirmDiscard().then((ok): unknown => ok && load(listing.parent!))}
+          title={t("files.up")}
+          aria-label={t("files.up")}
+        >
+          <Icon name="folder-up" />
+        </button>
         {crumbs.map((c, i) => {
           const path = i === 0 ? c : `${crumbs[0]}/${crumbs.slice(1, i + 1).join("/")}`;
           return (