Add context injection system (Milestone 3)

- Add src/core/context.ts with context gathering, ranking, and formatting
- Add src/core/config.ts for persistent configuration storage
- Add CLI commands: cortex context, cortex context-hook, cortex config
- Add memory_context MCP tool for Claude Code integration
- Add GET /api/context endpoint
- Include summary.ts from main branch for heartbeat dependency

src/cli/index.ts

@@ -11,6 +11,8 @@ import { graphCommand } from './commands/graph';
 import { serveCommand } from './commands/serve';
 import { decayCommand } from './commands/decay';
 import { childrenCommand } from './commands/children';
+import { contextCommand, contextHookCommand } from './commands/context';
+import { configCommand } from './commands/config';
 import { closeDb } from '../core/db';
 
 const program = new Command();
@@ -31,6 +33,9 @@ program.addCommand(graphCommand);
 program.addCommand(serveCommand);
 program.addCommand(decayCommand);
 program.addCommand(childrenCommand);
+program.addCommand(contextCommand);
+program.addCommand(contextHookCommand);
+program.addCommand(configCommand);
 
 program.hook('postAction', () => {
   closeDb();