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

libexec/devdesk-lib.sh

@@ -183,6 +183,18 @@ dd_registry_set_dir() {
         --arg n "$1" --arg d "$2" --arg t "$(date -Is)"
 }
 
+# Remote Control for session NAME (devdesk#61): its own choice if it made one,
+# else the default set in Settings (state settings.json), else
+# DEVDESK_REMOTE_CONTROL from the env files. Prints 1 or 0.
+dd_rc_wanted() {
+    local own def
+    # (not dd_registry_get: its `// empty` would turn false into "unset")
+    own=$(jq -Mr --arg n "$1" '.sessions[$n].remote_control | if . == null then empty else tostring end' "$DEVDESK_REGISTRY" 2>/dev/null)
+    case $own in true) echo 1; return ;; false) echo 0; return ;; esac
+    def=$(jq -rM '.remote_control_default // empty' "$DEVDESK_STATE_DIR/settings.json" 2>/dev/null)
+    case $def in true) echo 1 ;; false) echo 0 ;; *) [ "${DEVDESK_REMOTE_CONTROL:-0}" = 1 ] && echo 1 || echo 0 ;; esac
+}
+
 dd_registry_set_claude() {
     dd_registry_update '.sessions[$n] = ((.sessions[$n] // {}) + {claude_session_id: $id, claude_source: $src, updated: $t})' \
         --arg n "$1" --arg id "$2" --arg src "$3" --arg t "$(date -Is)"