Move exec to HookAPI, sessionManager/modelRegistry to HookEventContext

Breaking changes:
- HookEventContext now has sessionManager and modelRegistry (moved from SessionEventBase)
- HookAPI now has exec() method (moved from HookEventContext/HookCommandContext)
- HookRunner constructor takes sessionManager and modelRegistry as required params
- Session events no longer include sessionManager/modelRegistry fields

Hook code migration:
- event.sessionManager -> ctx.sessionManager
- event.modelRegistry -> ctx.modelRegistry
- ctx.exec() -> pi.exec()

Updated:
- src/core/hooks/types.ts - type changes
- src/core/hooks/runner.ts - constructor, createContext
- src/core/hooks/loader.ts - add exec to HookAPI
- src/core/sdk.ts - pass sessionManager/modelRegistry to HookRunner
- src/core/agent-session.ts - remove sessionManager/modelRegistry from events
- src/modes/* - remove setSessionFile calls, update events
- examples/hooks/* - update to new API

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -127,7 +127,6 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 	const hookRunner = session.hookRunner;
 	if (hookRunner) {
 		hookRunner.setUIContext(createHookUIContext(), false);
-		hookRunner.setSessionFile(session.sessionFile);
 		hookRunner.onError((err) => {
 			output({ type: "hook_error", hookPath: err.hookPath, event: err.event, error: err.error });
 		});
@@ -143,8 +142,6 @@ export async function runRpcMode(session: AgentSession): Promise<never> {
 		// Emit session event
 		await hookRunner.emit({
 			type: "session",
-			sessionManager: session.sessionManager,
-			modelRegistry: session.modelRegistry,
 			reason: "start",
 		});
 	}