fix: address five valid review findings; skip two

Fixed:
- march-madness/requirements.txt: Pillow>=10.3.0 (patches CVE-2024-28219;
  10.3.0 is the actual fix version — reviewer cited 12.2.0 but that risks
  breaking API changes without test coverage)
- wifi_monitor_daemon.py: add missing `import subprocess`; subprocess.run
  and CalledProcessError would NameError at runtime on the NM restart path
- wifi_manager.py: validate ap_idle_timeout_minutes before arithmetic —
  coerce to int, clamp 1–1440, fall back to 15 on bad config values
- wifi_manager.py: call _remove_nm_dnsmasq_captive_conf() on all three
  rollback paths in _enable_ap_mode_nmcli_hotspot() and in the top-level
  except block so stale dnsmasq drop-ins are never left behind
- api_v3.py: fix wrong_password prefix strip — removeprefix("wrong_password:")
  then lstrip() handles both "wrong_password: msg" and "wrong_password:msg"
- plugins_manager.js: add .catch() to loadInstalledPlugins().then() to
  surface failures instead of silently dropping unhandled rejections

Skipped:
- WiFiManager AP state persistence: architectural overhaul; _is_ap_mode_active()
  already derives from live system state, not in-memory variables
- Absolute subprocess paths in api_v3.py: paths vary by distro (/usr/bin vs
  /bin); web service has a normal PATH; sudoers already use resolved paths

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web_interface/blueprints/api_v3.py

@@ -7135,7 +7135,7 @@ def connect_wifi():
             # Propagate structured error type so the captive portal UI can show
             # "Wrong password — try again" instead of a generic failure message.
             error_type = "wrong_password" if (message or "").startswith("wrong_password:") else "connection_failed"
-            clean_message = (message or "").removeprefix("wrong_password: ") or "Failed to connect to network"
+            clean_message = (message or "").removeprefix("wrong_password:").lstrip() or "Failed to connect to network"
             return jsonify({
                 'status': 'error',
                 'message': clean_message,