feat: session status at a glance, file & image drop, live Ops Alerts (0.4.0)

- devdesk-state-hook (Claude UserPromptSubmit/PostToolUse/Notification/Stop/
  SessionStart/SessionEnd) records whether each session is working, waiting on
  you or idle; --list carries it. The sidebar shows it, the header shows the
  current session's state, and a pulsing "needs you" chip jumps to sessions
  waiting for input. Session refresh no longer depends on the sidebar being open.
- `devdesk attach --upload SESSION FILE BYTES` receives a file as base64
  terminal input (raw mode, exact length, size-checked, sanitised name) into
  /var/lib/devdesk/uploads/<session>/. The UI uploads dropped or pasted files and
  pastes the path into Claude, which attaches images itself.
- `devdesk alerts` / `--alerts`: firing and pending Grafana alert rules with
  severity, instances, summary and a link. The panel's "Ask Claude" types an
  investigation prompt into the current session.

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

etc/env

@@ -23,6 +23,12 @@ DEVDESK_DEFAULT_DIR=
 DEVDESK_GITEA_URL=https://code.lotusguild.org
 DEVDESK_GITEA_ALIASES=10.10.10.63
 
+# Grafana for the Ops Alerts panel (firing/pending alert rules). A Viewer
+# service-account token goes in DEVDESK_GRAFANA_TOKEN_FILE (mode 600).
+DEVDESK_GRAFANA_URL=http://10.10.10.49:3000
+DEVDESK_GRAFANA_PUBLIC_URL=https://dashboard.lotusguild.org
+DEVDESK_GRAFANA_TOKEN_FILE=/etc/devdesk/grafana-token
+
 # Claude Code binary and extra arguments for every session.
 CLAUDE_BIN=/root/.local/bin/claude
 CLAUDE_ARGS=