Workstream 3: Content & Capabilities System

## Content & Capabilities

### Tasks
- [ ] Create content.wit with content variants
- [ ] Create capabilities.wit with all MCP capabilities
- [ ] Add ToolAnnotations and ResourceAnnotations

### Dependencies
Depends on Workstream 1

### Acceptance Criteria
- Complete content type system
- All MCP 2025-06-18 capabilities

### Priority
🟠 High