feat: v0.12.0 Settings window, per-session Remote Control, delete conversations

- Settings (⋯ → Settings…, palette): theme, terminal text size, interface
  size, notifications, Remote Control & privacy. The ⋯ menu shrinks.
- Remote Control per session: registry choice > Settings default >
  DEVDESK_REMOTE_CONTROL. Switching an idle session restarts its Claude
  on the same conversation; busy sessions change at the next start.
  rc_active comes from the running process; RC tag on sessions.
- --delete-convo: remove a conversation's local transcript and subagent
  files; refused while in use. Delete… in Search past conversations.
Closes #61

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WHRLCCdXYm41Qx5kNhehaP

web/src/sessions.js

@@ -321,6 +321,8 @@ export class SessionsPanel {
       el('button', { class: 'dd-session-open', type: 'button', title, onclick: () => this.hooks.onOpen(s.name) },
         el('span', { class: `lt-dot ${status.dot}` }),
         el('span', { class: 'dd-session-name' }, s.name,
+          // Remote Control on: synced to claude.ai and the Claude app (devdesk#61).
+          s.rc_active ? el('span', { class: 'dd-tag dd-rc', title: 'Remote Control is on: this session syncs to claude.ai and the Claude app. Change it in Settings.' }, 'RC') : null,
           s.worktree ? el('span', { class: 'dd-tag dd-wt', title: `Own worktree on ${s.worktree.branch}\n${s.worktree.path}` }, `⑂ ${s.worktree.branch.replace(/^devdesk\//, '')}`) : null,
           s.tags?.length ? el('span', { class: 'dd-tags', title: 'Hosts this session worked on' }, ...s.tags.slice(0, 3).map((t) => el('span', { class: 'dd-tag' }, t))) : null,
           // The pull request of this branch (devdesk#25)