feat: v0.9.2 Ask Claude on an alert starts an investigation session

- Ops Alerts → Ask Claude now calls `devdesk attach --investigate SESSION UID`.
  The server looks the alert up, writes the prompt and starts Claude in a new
  alert-<name> session with it as the first prompt, already sent. Prompts are
  stored in prompts/<session>.txt and consumed once by devdesk-claude-run.
  A session that is already running is just opened.
- The prompt has the rule, query, summary, details and labels, and where it
  runs: the CT/VM id, the node it is on now, status and HA state, and
  `ssh <node> pct exec <id> --`. It reminds Claude that HA guests move
  (`devdesk guests <id>`), and gives aggregate rules a hint.
- `devdesk guests`: Proxmox inventory over SSH (DEVDESK_PVE_NODES). pvesh
  gives the cluster view; each node gives lxc-info and guest-agent IPs.
  Cached in guests.json, keeping last-seen IPs for stopped guests; --alerts
  refreshes it in the background every 5 minutes.
- Alerts carry uid, query, description and targets, matched by instance
  IP/host or by name; each card shows the target.
- cmd_alerts moves to libexec/devdesk-ops.sh.

Closes #39

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

libexec/devdesk-lib.sh

@@ -54,6 +54,7 @@ dd_load_env
 : "${DEVDESK_GRAFANA_URL:=}"
 : "${DEVDESK_GRAFANA_PUBLIC_URL:=$DEVDESK_GRAFANA_URL}"
 : "${DEVDESK_GRAFANA_TOKEN_FILE:=/etc/devdesk/grafana-token}"
+: "${DEVDESK_PVE_NODES:=}"
 : "${DEVDESK_UPLOAD_MAX:=26214400}"
 : "${DEVDESK_PUBLIC_URL:=}"
 : "${DEVDESK_MATRIX_WEBHOOK_FILE:=/etc/devdesk/matrix-webhook}"
@@ -188,7 +189,7 @@ dd_registry_set_claude() {
 dd_registry_remove() {
     dd_registry_update 'del(.sessions[$n])' --arg n "$1"
     rm -f "$DEVDESK_CONTEXT_DIR/$1.json" "$DEVDESK_STATUS_DIR/$1.json" "$DEVDESK_STATE_DIR/edits/$1.txt" \
-        "$DEVDESK_STATE_DIR/commands/$1.jsonl" "$DEVDESK_STATE_DIR/tags/$1.json"
+        "$DEVDESK_STATE_DIR/commands/$1.jsonl" "$DEVDESK_STATE_DIR/tags/$1.json" "$DEVDESK_STATE_DIR/prompts/$1.txt"
 }
 
 dd_registry_rename() {
@@ -201,7 +202,7 @@ dd_registry_rename() {
         fi
     done
     local f
-    for f in "edits/%s.txt" "commands/%s.jsonl" "tags/%s.json"; do
+    for f in "edits/%s.txt" "commands/%s.jsonl" "tags/%s.json" "prompts/%s.txt"; do
         # shellcheck disable=SC2059 # the pattern is ours
         if [ -f "$DEVDESK_STATE_DIR/$(printf "$f" "$1")" ]; then
             # shellcheck disable=SC2059