Add todo hook companion to todo custom tool

- /todos command displays all todos on current branch with custom UI
- Update hooks.md to clarify components must not be wrapped in Box/Container
- Cross-reference tool and hook in example READMEs

.pi/settings.json

@@ -1,3 +1,4 @@
 {
-  "customTools": ["packages/coding-agent/examples/custom-tools/todo/index.ts"]
+  "customTools": ["packages/coding-agent/examples/custom-tools/todo/index.ts"],
+  "hooks": ["packages/coding-agent/examples/hooks/todo/index.ts"]
 }