feat(mcp) : add MCP resources, documentation, and .mcp.json config

- 3 MCP resources: schema, roles, stats
- docs/mcp/README.md with full user guide (config, tools catalogue, workflows)
- .mcp.json for Claude Code stdio transport
- Design spec and implementation plan

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.mcp.json

@@ -0,0 +1,14 @@
+{
+  "mcpServers": {
+    "inventory": {
+      "command": "docker",
+      "args": [
+        "exec", "-i",
+        "-e", "MCP_PROFILE_ID=REPLACE_WITH_YOUR_PROFILE_ID",
+        "-e", "MCP_PROFILE_PASSWORD=REPLACE_WITH_YOUR_PASSWORD",
+        "php-inventory-apache",
+        "php", "bin/console", "mcp:server"
+      ]
+    }
+  }
+}