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-claude-run

@@ -42,12 +42,21 @@ run_new() {
 }
 
 run_resume() {
-    local id args started rc fork=()
+    local id args fork=()
     id=$(dd_registry_get "$NAME" claude_session_id)
     if [ -z "$id" ]; then
         run_new
         return
     fi
+    # Start fresh only when the conversation's file is really gone. Any other
+    # failure (an early Ctrl+C, a network error) leaves the recorded id alone
+    # and ends at the menu, where ⏎ tries again (devdesk#12).
+    if [ -z "$(dd_convo_file "$id")" ]; then
+        printf "%sConversation %s is no longer in Claude's history — starting a new one.%s\n" "$MUTED" "$id" "$RESET"
+        sleep 1
+        run_new
+        return
+    fi
     mapfile -d '' args < <(common_args)
     # "Fork" from conversation search (devdesk#24): continue as a new
     # conversation, once; the SessionStart hook then records the new id.
@@ -56,17 +65,7 @@ run_resume() {
         # shellcheck disable=SC2016 # $n is a jq variable
         dd_registry_update 'del(.sessions[$n].fork)' --arg n "$NAME" 2>/dev/null || true
     fi
-    started=$SECONDS
     "$CLAUDE_BIN" --resume "$id" "${fork[@]}" "${args[@]}"
-    rc=$?
-    # A resume that fails straight away means the transcript is gone; start fresh.
-    if [ "$rc" -ne 0 ] && [ $((SECONDS - started)) -lt 10 ]; then
-        printf '%sCould not resume conversation %s — starting a new one.%s\n' "$MUTED" "$id" "$RESET"
-        sleep 1
-        run_new
-        return
-    fi
-    return "$rc"
 }
 
 menu() {