feat: add comprehensive loading feedback (#18)

AGENTS.md

@@ -88,6 +88,7 @@ Use the single-context documentation layout. See [domain.md](file:///home/nessar
 - Keep component styles scoped unless a style is intentionally global.
 - Ensure layouts work across supported viewport sizes.
 - Provide explicit loading, empty, success, and error states.
+- Every user-observable asynchronous frontend operation must expose a truthful loading lifecycle. Prefer content-shaped skeletons for first loads, preserve established content with subtle busy feedback during refreshes, and use operation-local progress for actions so unrelated work remains available; never present pending or failed data as an empty or successful result.
 - Avoid unexpected layout shifts and blocking interactions.
 
 ### Accessibility