refactor: ai-proj-plugin 移至 skills-core，合并冗余 session 插件

- ai-proj-plugin 作为 MCP 基础设施移入 skills-core/
- 删除 4 个冗余 session 子插件（save/reload/read/search），
  session-plugin 已包含全部功能
- 48 → 44 插件

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -10,6 +10,19 @@
     "pluginRoot": "."
   },
   "plugins": [
+    {
+      "name": "ai-proj-plugin",
+      "source": "./skills-core/ai-proj-plugin",
+      "description": "AI project management via REST API. Works out of the box!",
+      "version": "2.0.1",
+      "category": "productivity",
+      "keywords": [
+        "project-management",
+        "tasks",
+        "requirements"
+      ],
+      "strict": false
+    },
     {
       "name": "agent-swarm-plugin",
       "source": "./skills-dev/agent-swarm-plugin",
@@ -457,71 +470,6 @@
       ],
       "strict": false
     },
-    {
-      "name": "ai-proj-plugin",
-      "source": "./skills-workflow/ai-proj-plugin",
-      "description": "AI project management via REST API. Works out of the box!",
-      "version": "2.0.1",
-      "category": "productivity",
-      "keywords": [
-        "project-management",
-        "tasks",
-        "requirements"
-      ],
-      "strict": false
-    },
-    {
-      "name": "read-session-plugin",
-      "source": "./skills-workflow/read-session-plugin",
-      "description": "Plugin for read-session",
-      "version": "1.0.0",
-      "category": "workflow",
-      "keywords": [
-        "session",
-        "workflow",
-        "productivity"
-      ],
-      "strict": false
-    },
-    {
-      "name": "reload-session-plugin",
-      "source": "./skills-workflow/reload-session-plugin",
-      "description": "Plugin for reload-session",
-      "version": "1.0.0",
-      "category": "workflow",
-      "keywords": [
-        "session",
-        "workflow",
-        "productivity"
-      ],
-      "strict": false
-    },
-    {
-      "name": "save-session-plugin",
-      "source": "./skills-workflow/save-session-plugin",
-      "description": "Plugin for save-session",
-      "version": "1.0.0",
-      "category": "workflow",
-      "keywords": [
-        "session",
-        "workflow",
-        "productivity"
-      ],
-      "strict": false
-    },
-    {
-      "name": "search-sessions-plugin",
-      "source": "./skills-workflow/search-sessions-plugin",
-      "description": "Plugin for search-sessions",
-      "version": "1.0.0",
-      "category": "workflow",
-      "keywords": [
-        "session",
-        "workflow",
-        "productivity"
-      ],
-      "strict": false
-    },
     {
       "name": "session-plugin",
       "source": "./skills-workflow/session-plugin",