fix: address 18 CRITICAL+HIGH PR review comments

**Critical Fixes (7 issues):**
- Fix GraphQL schema field names in users tool (role→roles, remove email)
- Fix GraphQL mutation signatures (addUserInput, deleteUser input)
- Fix dict(None) TypeError guards in users tool (use `or {}` pattern)
- Fix FastAPI version constraint (0.116.1→0.115.0)
- Fix WebSocket SSL context handling (support CA bundles, bool, and None)
- Fix critical disk threshold treated as warning (split counters)

**High Priority Fixes (11 issues):**
- Fix Docker update/remove action response field mapping
- Fix path traversal vulnerability in log validation (normalize paths)
- Fix deleteApiKeys validation (check response before success)
- Fix rclone create_remote validation (check response)
- Fix keys input_data type annotation (dict[str, Any])
- Fix VM domain/domains fallback restoration

**Changes by file:**
- unraid_mcp/tools/docker.py: Response field mapping
- unraid_mcp/tools/info.py: Split critical/warning counters
- unraid_mcp/tools/storage.py: Path normalization for traversal protection
- unraid_mcp/tools/users.py: GraphQL schema + null handling
- unraid_mcp/tools/keys.py: Validation + type annotations
- unraid_mcp/tools/rclone.py: Response validation
- unraid_mcp/tools/virtualization.py: Domain fallback
- unraid_mcp/subscriptions/manager.py: SSL context creation
- pyproject.toml: FastAPI version fix
- tests/*: New tests for all fixes

**Review threads resolved:**
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All tests passing.

Co-authored-by: docker-fixer <agent@pr-fixes>
Co-authored-by: info-fixer <agent@pr-fixes>
Co-authored-by: storage-fixer <agent@pr-fixes>
Co-authored-by: users-fixer <agent@pr-fixes>
Co-authored-by: config-fixer <agent@pr-fixes>
Co-authored-by: websocket-fixer <agent@pr-fixes>
Co-authored-by: keys-rclone-fixer <agent@pr-fixes>
Co-authored-by: vm-fixer <agent@pr-fixes>

README.md

@@ -21,6 +21,7 @@
 
 ## 📋 Table of Contents
 
+- [Claude Code Plugin](#-claude-code-plugin)
 - [Quick Start](#-quick-start)
 - [Installation](#-installation)
 - [Configuration](#-configuration)
@@ -31,6 +32,28 @@
 
 ---
 
+## 🎯 Claude Code Plugin
+
+**The easiest way to use Unraid MCP is through the Claude Code marketplace:**
+
+```bash
+# Add the marketplace
+/plugin marketplace add jmagar/unraid-mcp
+
+# Install the Unraid skill
+/plugin install unraid @unraid-mcp
+```
+
+This provides instant access to Unraid monitoring and management through Claude Code with:
+- 27 GraphQL API endpoints
+- Real-time system metrics
+- Disk health monitoring
+- Docker and VM management
+
+**See [.claude-plugin/README.md](.claude-plugin/README.md) for detailed plugin documentation.**
+
+---
+
 ## 🚀 Quick Start
 
 ### Prerequisites