Tools now use ExtensionRunner.createContext() instead of a separate
inline context factory. This ensures tools and event handlers share
the same context, fixing ctx.shutdown() and other context methods.
- Made ExtensionRunner.createContext() public
- Changed wrapRegisteredTools to accept ExtensionRunner instead of getContext callback
- Create ExtensionRunner when SDK custom tools are present (not just extensions)
- Removed redundant inline context factory from sdk.ts
New src/core/extensions/ directory with:
- types.ts: merged types from hooks and custom-tools
- loader.ts: single loader for extensions
- runner.ts: ExtensionRunner for event emission
- wrapper.ts: tool wrapping utilities
- index.ts: exports
Key changes from old system:
- Single ExtensionAPI with registerTool() for LLM-callable tools
- Tools use ExtensionContext (has UI access)
- No onSession callback on tools (use pi.on events instead)
refs #454
