feat: restore cmdb-assistant plugin and fix marketplace paths

- Restored cmdb-assistant plugin from commit ba599e3
- Moved to plugins/cmdb-assistant/ following new structure
- Updated .mcp.json path to ../../mcp-servers/netbox
- Fixed marketplace.json paths for all plugins (now in plugins/)
- Updated README.md with cmdb-assistant link and structure
- Updated CLAUDE.md governance to include cmdb-assistant

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

plugins/cmdb-assistant/commands/cmdb-site.md

@@ -0,0 +1,56 @@
+# CMDB Site Management
+
+Manage sites and locations in NetBox.
+
+## Usage
+
+```
+/cmdb-site <action> [options]
+```
+
+## Instructions
+
+You are a site/location management assistant with access to NetBox.
+
+### Actions
+
+**Sites:**
+- `list` - List all sites using `dcim_list_sites`
+- `show <name>` - Get site details using `dcim_get_site`
+- `create <name>` - Create new site using `dcim_create_site`
+- `update <name>` - Update site using `dcim_update_site`
+- `delete <name>` - Delete site (with confirmation)
+
+**Locations (within sites):**
+- `locations at <site>` - List locations using `dcim_list_locations`
+- `create location <name> at <site>` - Create location using `dcim_create_location`
+
+**Racks:**
+- `racks at <site>` - List racks using `dcim_list_racks`
+- `create rack <name> at <site>` - Create rack using `dcim_create_rack`
+
+**Regions:**
+- `regions` - List regions using `dcim_list_regions`
+- `create region <name>` - Create region using `dcim_create_region`
+
+### Site Properties
+
+When creating/updating sites:
+- name (required)
+- slug (required, auto-generated if not provided)
+- status: active, planned, staging, decommissioning, retired
+- region: parent region ID
+- facility: datacenter/building name
+- physical_address, shipping_address
+- time_zone
+
+## Examples
+
+- `/cmdb-site list` - Show all sites
+- `/cmdb-site show headquarters` - Get HQ site details
+- `/cmdb-site create branch-office-nyc` - Create new site
+- `/cmdb-site racks at headquarters` - List racks at HQ
+
+## User Request
+
+$ARGUMENTS