Add before/after session events with cancellation support

- Merge branch event into session with before_branch/branch reasons
- Add before_switch, before_clear, shutdown reasons
- before_* events can be cancelled with { cancel: true }
- Update RPC commands to return cancelled status
- Add shutdown event on process exit
- New example hooks: confirm-destructive, dirty-repo-guard, auto-commit-on-exit

fixes #278

packages/ai/src/models.generated.ts

@@ -3223,9 +3223,9 @@ export const MODELS = {
 			reasoning: true,
 			input: ["text"],
 			cost: {
-				input: 0.24,
-				output: 0.38,
-				cacheRead: 0.02,
+				input: 0.23900000000000002,
+				output: 0.378,
+				cacheRead: 0.11,
 				cacheWrite: 0,
 			},
 			contextWindow: 163840,