docs(skill): document sendNotification action (7 actions total) + CLI support

- skill: SKILL.md (7 actions in description + routing table entry), action-types.md
  (new section #4 sendNotification: config keys, variables, system-in-app semantics),
  automation-guide.md/cli-reference.md (--to-user/--title/--message/--severity/--path),
  development.md (7 actions), metadata.json abstract
- cli: action add --type sendNotification now builds config from granular flags
  (toUserId/title/message/severity/path); ACTION_TYPES includes sendNotification;
  live-verified via workflow create + action add + delete

src/commands/workflow.ts

@@ -417,6 +417,7 @@ const ACTION_TYPES = [
   'createRecord',
   'updateRecord',
   'getRecords',
+  'sendNotification',
 ] as const;
 
 export function actionCommand(): Command {
@@ -445,6 +446,11 @@ export function actionCommand(): Command {
     .option('--target-table <id>', 'Target table id (createRecord/updateRecord/getRecords)')
     .option('--records <json>', 'Records JSON array (createRecord/updateRecord)')
     .option('--query <json>', 'Query JSON (getRecords)')
+    .option('--to-user <id>', 'Recipient user id (sendNotification)')
+    .option('--title <s>', 'Notification title (sendNotification)')
+    .option('--message <s>', 'Notification message (sendNotification)')
+    .option('--severity <s>', 'Notification severity info|warning|critical (sendNotification)')
+    .option('--path <s>', 'Click-through path, e.g. /base/xx/table/yy (sendNotification)')
     .option('--name <n>', 'Optional node display name')
     .option('--base-id <id>', 'Base id (overrides default)')
     .action(
@@ -652,6 +658,14 @@ export function buildActionConfig(opts: Record<string, string>): Record<string,
       if (opts.query) config.query = JSON.parse(opts.query);
       break;
     }
+    case 'sendNotification': {
+      if (opts.toUser) config.toUserId = opts.toUser;
+      if (opts.title) config.title = opts.title;
+      if (opts.message) config.message = opts.message;
+      if (opts.severity) config.severity = opts.severity;
+      if (opts.path) config.path = opts.path;
+      break;
+    }
     default:
       break;
   }