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/metadata.json

@@ -3,7 +3,7 @@
   "organization": "inkreach",
   "authors": ["inkreach"],
   "tags": ["database", "teable", "no-code", "automation", "self-hosted"],
-  "abstract": "Operate a deployed inkreach-teable instance — configure tables, fields, records, views, and the self-built automation engine (8 triggers + 6 actions), plus development/deployment knowledge. Uses the inkreach-teable CLI which targets the project's own automation contract (not official teable CLI compatible).",
+  "abstract": "Operate a deployed inkreach-teable instance — configure tables, fields, records, views, and the self-built automation engine (8 triggers + 7 actions), plus development/deployment knowledge. Uses the inkreach-teable CLI which targets the project's own automation contract (not official teable CLI compatible).",
   "engines": {
     "inkreachTeableCli": ">=0.1"
   },