test(10-05): bring every SPA module, composable and component under Vitest

- 41 unit and component suites under admin/tests/{app,state,shell,list,form,relation,views,ui}
  covering states and a11y roles; every src module is imported by a test
- typed fixture helper assigns each JSON fixture to its generated OpenAPI type
- fix: iconFor ignores inherited object members such as "constructor"
- fix: field controls import ./control instead of the registry (import cycle
  left a renderer unregistered depending on module load order)
- fix: dropdown shows the placeholder for an unknown stored value next to an emptyOption
- fix: list announces a failed schema load even when the rows arrive after it
- tailwind no longer scans admin/tests; boardwalk/dist rebuilt

admin/src/styles/main.css

@@ -2,9 +2,11 @@
 
 /* The generated API document and types carry prose, not classes: keep them
    out of the class scan so an admin API change does not churn the built CSS
-   in boardwalk/dist (D-04 drift check). */
+   in boardwalk/dist (D-04 drift check). Tests are not shipped either: words
+   in test code (a "blur" event, say) must never add utilities to the bundle. */
 @source not "../api/schema.d.ts";
 @source not "../../openapi";
+@source not "../../tests";
 
 /* Self-hosted fonts (D-07). Whole-weight files carry latin and latin-ext with
    unicode-range, so Polish diacritics and basic Latin both resolve. */