Cursor prompt: Add Capability Provider TypeScript interfaces

Prerequisites

Read:

• [ ] platform/CAPABILITY_PROVIDERS.md
• [ ] 0005-capability-provider-plugin-model.md

Non-goals

• Rust plugin host
• Dynamic plugin loading

Current state

• No capability registry

Tasks

1. Create extension/webview-ui/src/capabilities/types.ts with CapabilityProvider base + ReasoningProvider, QueryProvider stubs
2. Create extension/webview-ui/src/capabilities/registry.ts with register/list
3. Register built-in 'ontocore' stubs that delegate to existing LSP calls
4. Add capabilities/registry.test.ts

Acceptance criteria

• [ ] Built-in providers registered
• [ ] Types export cleanly

Tests

• cd extension/webview-ui && npm test

Do not

• Do not implement WASM/IPC sandbox

References

• Cursor prompts index