fix: address five review findings (Pillow CVEs, daemon exception narrowing, timeout handling, plugin store)

- march-madness/requirements.txt: Pillow>=12.2.0 (patches CVE-2026-42308
  and CVE-2026-42310; previous floor of 10.3.0 was insufficient)

- wifi_monitor_daemon: narrow final except Exception to
  (subprocess.SubprocessError, OSError) so programming errors in the NM
  restart block are no longer silently swallowed

- api_v3/execute_system_action: add explicit subprocess.TimeoutExpired
  handler before the generic Exception catch; returns action-specific
  message with 'status','message','returncode','stdout','stderr' fields
  so the UI receives a precise, actionable payload instead of the generic
  'Failed to execute system action' string

- plugins_manager.js: move searchPluginStore into .finally() so the
  plugin store renders regardless of whether loadInstalledPlugins succeeds
  or fails; .catch() still logs the error

- first_time_install.sh: add safe_plugin_rm.sh NOPASSWD rule to the
  /tmp/ledmatrix_web_sudoers block; configure_web_sudo.sh had this rule
  but the standalone installer never granted it, leaving plugin removal
  broken after first-time install

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

scripts/utils/wifi_monitor_daemon.py

@@ -155,7 +155,7 @@ class WiFiMonitorDaemon:
                                 logger.error(f"NetworkManager restart failed (rc={e.returncode}); "
                                              "resetting failure counter to avoid tight retry loop")
                                 self._consecutive_internet_failures = 0
-                            except Exception as e:
+                            except (subprocess.SubprocessError, OSError) as e:
                                 logger.error(f"NetworkManager restart error: {e}; "
                                              "resetting failure counter to avoid tight retry loop")
                                 self._consecutive_internet_failures = 0