Add retained state, Data Controller, and Resource lifecycle applications under examples, with paired guidance and public-path interaction tests.
Verified with make check (57 behavior tests and 5 docs tests), make load, byte compilation, checkdoc, and GUI width checks at 784px body width.
Deliver the unified View and Component model with retained Runtime, reactive scopes, Context, Behaviors, events, Actions, styles, Resources, Data, official UI Components, and Playground examples.\n\nVerification: make check and make load pass in the independent repository; sibling Ebox core tests pass 544/544.
