fix(ux): resolve tickets #55 #56 — resource modal stability and success feedback

#55: Add SuccessToast after new resource is created. ResourceModal gains an
optional onSuccess(displayName) prop; ResourcesClient wires it to a toast
that auto-dismisses after 2.5 s.

#56: Fix useFocusTrap stale-closure bug. Focusable elements are now queried
dynamically inside handleKeyDown (not captured once at mount), so Tab
navigation stays correct as the form re-renders. Initial focus is deferred
via requestAnimationFrame so the browser layout is stable before focus() fires.

Co-Authored-By: claude-flow <ruv@ruv.net>

apps/web/src/hooks/useFocusTrap.ts

@@ -8,16 +8,22 @@ export function useFocusTrap(ref: React.RefObject<HTMLElement | null>, isOpen: b
     if (!isOpen || !ref.current) return;
     const el = ref.current;
 
-    const focusable = Array.from(el.querySelectorAll<HTMLElement>(FOCUSABLE_SELECTOR));
-    const first = focusable[0];
-    const last = focusable[focusable.length - 1];
-
-    // Focus first element when modal opens
-    first?.focus();
+    // Defer initial focus to the next animation frame so the browser layout is
+    // complete before we attempt to focus — prevents intermittent failures when
+    // the modal DOM has just been mounted.
+    const rafId = requestAnimationFrame(() => {
+      const focusable = Array.from(el.querySelectorAll<HTMLElement>(FOCUSABLE_SELECTOR));
+      focusable[0]?.focus();
+    });
 
     function handleKeyDown(e: KeyboardEvent) {
       if (e.key !== "Tab") return;
+      // Re-query on every keydown so the list is always current — form state can
+      // toggle disabled attributes and add/remove sections during a session.
+      const focusable = Array.from(el.querySelectorAll<HTMLElement>(FOCUSABLE_SELECTOR));
       if (focusable.length === 0) { e.preventDefault(); return; }
+      const first = focusable[0];
+      const last = focusable[focusable.length - 1];
       if (e.shiftKey) {
         if (document.activeElement === first) { e.preventDefault(); last?.focus(); }
       } else {
@@ -26,6 +32,9 @@ export function useFocusTrap(ref: React.RefObject<HTMLElement | null>, isOpen: b
     }
 
     el.addEventListener("keydown", handleKeyDown);
-    return () => el.removeEventListener("keydown", handleKeyDown);
+    return () => {
+      cancelAnimationFrame(rafId);
+      el.removeEventListener("keydown", handleKeyDown);
+    };
   }, [isOpen, ref]);
 }