feat: biến repo thành marketplace Claude Code nội bộ (smartgift-all/dev/common) + hướng dẫn cài

.claude-plugin/marketplace.json

@@ -0,0 +1,29 @@
+{
+  "$schema": "https://anthropic.com/claude-code/marketplace.schema.json",
+  "name": "smartgift",
+  "description": "Smartgift internal Claude Code skills. Pick per role: smartgift-dev for the dev team, smartgift-common for all staff, or install both.",
+  "owner": {
+    "name": "Smartgift",
+    "email": "vinnt@smartgift.vn"
+  },
+  "plugins": [
+    {
+      "name": "smartgift-all",
+      "source": "./plugins/all",
+      "description": "Toàn bộ — cả md-writing lẫn prompt-sharpening. Cài cái này nếu muốn tất cả.",
+      "category": "workflow"
+    },
+    {
+      "name": "smartgift-dev",
+      "source": "./plugins/dev",
+      "description": "Dev team — md-writing skill for authoring and maintaining CLAUDE.md / AGENTS.md rule files.",
+      "category": "workflow"
+    },
+    {
+      "name": "smartgift-common",
+      "source": "./plugins/common",
+      "description": "All staff — prompt-sharpening skill for disambiguating requests before acting.",
+      "category": "productivity"
+    }
+  ]
+}