fix(plugins): remove invalid mcp_servers key from plugin.json files

The mcp_servers key is not a valid key in the Claude plugin manifest
schema. MCP servers are configured in the root .mcp.json file instead.

Affected plugins:
- cmdb-assistant
- contract-validator
- data-platform
- pr-review
- projman
- viz-platform

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/cmdb-assistant/.claude-plugin/plugin.json

@@ -19,6 +19,5 @@
     "data-quality",
     "validation"
   ],
-  "mcp_servers": ["netbox"],
   "commands": ["./commands/"]
 }

plugins/contract-validator/.claude-plugin/plugin.json

@@ -17,6 +17,5 @@
     "interfaces",
     "cross-plugin"
   ],
-  "mcp_servers": ["contract-validator"],
   "commands": ["./commands/"]
 }

plugins/data-platform/.claude-plugin/plugin.json

@@ -18,6 +18,5 @@
     "etl",
     "dataframe"
   ],
-  "mcp_servers": ["data-platform"],
   "commands": ["./commands/"]
 }

plugins/pr-review/.claude-plugin/plugin.json

@@ -16,6 +16,5 @@
     "performance",
     "multi-agent"
   ],
-  "mcp_servers": ["gitea"],
   "commands": ["./commands/"]
 }

plugins/projman/.claude-plugin/plugin.json

@@ -16,6 +16,5 @@
     "agile",
     "lessons-learned"
   ],
-  "mcp_servers": ["gitea"],
   "commands": ["./commands/"]
 }

plugins/viz-platform/.claude-plugin/plugin.json

@@ -19,6 +19,5 @@
     "visualization",
     "dmc"
   ],
-  "mcp_servers": ["viz-platform"],
   "commands": ["./commands/"]
 }