fix: v0.9.1 robustness cleanups

- run_resume falls back to a new conversation only when the transcript file
  is gone; other failures end at the menu with the recorded id intact.
- The SessionStart hook resolves the session name under the registry lock;
  rename holds it across tmux rename-session and the registry move
  (dd_registry_locked, nestable).
- dd_load_env parses KEY=value like systemd instead of sourcing the files.
- devdesk-deploy: DPkg::Lock::Timeout, explicit FAILED lines on stdout and in
  the log; the hook answers synchronously and CI checks the HTTP status.
  logrotate for the deploy log.
- postinst drops duplicate terminal-features entries; hooks sweep stale
  temp files.

Closes #12

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

libexec/devdesk-session-hook

@@ -7,14 +7,20 @@
 # shellcheck source=libexec/devdesk-lib.sh
 . "${DEVDESK_LIBEXEC:-/usr/lib/devdesk}/devdesk-lib.sh" || exit 0
 
-session=$(dd_current_session)
-[ -n "$session" ] || exit 0
-dd_valid_name "$session" || exit 0
-
 input=$(cat)
 id=$(jq -r '.session_id // empty' <<<"$input" 2>/dev/null)
 source=$(jq -r '.source // empty' <<<"$input" 2>/dev/null)
 [ -n "$id" ] || exit 0
 
-dd_registry_set_claude "$session" "$id" "$source" 2>/dev/null
+# The session's name is read under the registry lock: a rename holds it too,
+# so the id can't land under the old name after the entry moved.
+# shellcheck disable=SC2317 # called through dd_registry_locked
+record() {
+    local session
+    session=$(dd_current_session)
+    if [ -z "$session" ] || ! dd_valid_name "$session"; then return 0; fi
+    dd_registry_set_claude "$session" "$id" "$source"
+}
+dd_registry_locked record 2>/dev/null
+dd_sweep_tmp
 exit 0