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>

first_time_install.sh

@@ -1110,6 +1110,7 @@ $ACTUAL_USER ALL=(ALL) NOPASSWD: $SYSTEMCTL_PATH restart ledmatrix-web.service
 $ACTUAL_USER ALL=(ALL) NOPASSWD: $PYTHON_PATH $PROJECT_ROOT_DIR/display_controller.py
 $ACTUAL_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT_DIR/start_display.sh
 $ACTUAL_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT_DIR/stop_display.sh
+$ACTUAL_USER ALL=(ALL) NOPASSWD: $BASH_PATH $PROJECT_ROOT_DIR/scripts/fix_perms/safe_plugin_rm.sh *
 EOF
 if [ -n "$JOURNALCTL_PATH" ]; then
     cat >> /tmp/ledmatrix_web_sudoers << EOF