style(html_examples): clean htmx-like shell with no low-level plumbing

- Move CSS out of app_shell.heml into app.css served by the app.
- Remove direct hemx::advanced::Effect import from example code; rely on IntoEffect.
- Update README to not mention raw Effect:: APIs.
- Keep generated resources and tiny runtime behavior only.

req: examples/001
req: htmx_equivalents/001
req: htmx_equivalents/002

examples/html_examples/README.md

@@ -51,7 +51,7 @@ Status legend:
 | `modal-custom` | deferred | A custom modal can be a generated partial plus focus/escape policy, but needs accessibility proof before copy/paste. | Later slice should include keyboard/focus tests. |
 | `tabs-hateoas` | deferred | Good hemx fit: server-owned selected tab and generated tab panel replacement; needs a focused slice. | Later slice should add one tab group. |
 | `tabs-javascript` | refused | Client-owned tab state is exactly what generated server-owned state is meant to avoid unless a product needs it. | Prefer `tabs-hateoas`. |
-| `keyboard-shortcuts` | integration-owned | Keyboard policy belongs to the app/host; hemx should only receive explicit events. | Use `Effect::event`/app JS when needed. |
+| `keyboard-shortcuts` | integration-owned | Keyboard policy belongs to the app/host; hemx should only receive explicit events. | Use generated app-level events / app JS when needed. |
 | `sortable` | integration-owned | Drag/drop ordering needs a browser library or pointer policy plus server reorder command. | Keep Sortable.js as app-owned integration until proven reusable. |
 | `update-other-content` | implemented | Generated effects can update multiple slots from one handler; validation and search already update status plus rows/errors. | `validate_email`, `search` handlers. |
 | `confirm` | integration-owned | Confirmation wording and irreversible-action policy belong to the app; hemx should not own a global confirm system. | Use native confirm/app dialog around generated delete forms. |