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

.agents/skills/inkreach-teable/api-reference/action-types.md

@@ -1,13 +1,13 @@
 # Action Types Reference
 
-All 6 actions of the inkreach-teable automation engine. Actions run in topological order after the trigger; each receives the merged upstream output.
+All 7 actions of the inkreach-teable automation engine. Actions run in topological order after the trigger; each receives the merged upstream output.
 
 An action node:
 ```json
 {
   "id": "node-2",
   "type": "action",
-  "category": "<one of the 6 types below>",
+  "category": "<one of the 7 types below>",
   "config": { ... },
   "name": null
 }
@@ -158,11 +158,40 @@ inkreach-teable action add <wfId> --type httpRequest \
 - GET/HEAD do not send a body.
 
 **Output:** `{ "statusCode": 200, "headers": {...}, "body": <parsed> }`
-- Non-2xx still returns output but the node status is `failed`.
 
 ---
 
-## 4. createRecord — Create records
+## 4. sendNotification — System in-app notification (站内信，非邮件)
+
+```bash
+inkreach-teable action add <wfId> --type sendNotification \
+  --to-user usr4ioKJl6XpZgyFhxW \
+  --title '新工单' --message '工单 {{n0.record.id}} 已创建' \
+  --severity info
+```
+
+**Config:**
+```json
+{
+  "toUserId": "usr4ioKJl6XpZgyFhxW",
+  "title": "新工单",
+  "message": "工单 {{n0.record.id}} 已创建",
+  "path": "/base/bseX/table/tblY",
+  "severity": "info"
+}
+```
+- `toUserId`: recipient user ID (required). Can reference the trigger user with `{{n0.user.id}}` (submitter/operator — only populated on user-initiated triggers; scheduled/webhook resolve to empty).
+- `title` + `message`: notification text; both support `{{nodeId.path}}` variables. If title set, rendered as `title\nmessage`.
+- `path` (optional): click-through URL in the notification center.
+- `severity`: `info` (default) | `warning` | `critical`.
+
+**IMPORTANT**: this is a **system in-app notification** (bell badge + notification center + realtime socket push). It calls `NotificationService.sendCommonNotify` with `type=system` and **no email config — no email is sent**. Prefer it over `sendEmail` unless an actual email is required.
+
+**Output:** `{ "sentCount": 1, "invalidUserIds": [], "toUserId": "usr..." }`
+
+---
+
+## 5. createRecord — Create records
 
 ```bash
 inkreach-teable action add <wfId> --type createRecord \
@@ -184,7 +213,7 @@ inkreach-teable action add <wfId> --type createRecord \
 
 ---
 
-## 5. updateRecord — Update records
+## 6. updateRecord — Update records
 
 ```bash
 inkreach-teable action add <wfId> --type updateRecord \
@@ -206,7 +235,7 @@ inkreach-teable action add <wfId> --type updateRecord \
 
 ---
 
-## 6. getRecords — Query records
+## 7. getRecords — Query records
 
 ```bash
 inkreach-teable action add <wfId> --type getRecords \