chore: drop the ccam entry — AgentHub ships its own marketplace

The entry pointed at Smartgift-AI/Claude-Code-Monitor, a repo name that has since been renamed to AgentHub, and it duplicated an install path AgentHub already publishes from its own marketplace. Two routes to the same plugin means a double install runs two hook-ingestion sets in parallel.

README now points at the AgentHub marketplace instead, and documents the migration: after the next 'marketplace update sg' an existing ccam@sg shows '✘ failed to load' and the dashboard stops receiving events until the user switches over.

.claude-plugin/marketplace.json

@@ -24,16 +24,6 @@
       "source": "./plugins/common",
       "description": "All staff — sg-prompt-sharpening skill for disambiguating requests before acting.",
       "category": "productivity"
-    },
-    {
-      "name": "ccam",
-      "source": {
-        "source": "url",
-        "url": "https://git.smartgift.io.vn/Smartgift-AI/Claude-Code-Monitor.git",
-        "ref": "main"
-      },
-      "description": "Claude Code Agent Monitor — the local-first dashboard as a plugin. Installs the event hooks, boots the dashboard server, puts the ccam CLI on PATH, and connects the MCP tools. No checkout, no npm run setup.",
-      "category": "monitoring"
     }
   ]
 }