fix: smooth mobile edit transition and align modal validation behavior (#286)

* fix: reliable Escape key close for all modals via useEscapeKey hook

- Add useEscapeKey hook (document-level keydown listener)
- Retrofit all 12 modal/overlay components to use it
- Remove redundant overlay onKeyDown Escape handlers
- Simplify modal-content onKeyDown to plain stopPropagation
- Replace MedDetailModal's capture-phase useEffect with 3 useEscapeKey calls
- Replace SharedSchedule's inline useEffect with useEscapeKey
- Add mandatory modal rules to UI Consistency skill
- All 777 frontend + 569 backend tests pass

* fix: smooth mobile edit transition and align modal validation behavior

* fix: keep overlay keydown non-closing for Enter key

* fix: show mobile name error when validation already exists

* fix: restore app-level escape priority handling

* fix: prioritize schedule lightbox on Escape

frontend/src/hooks/useEscapeKey.ts

@@ -0,0 +1,36 @@
+import { useEffect, useRef } from "react";
+
+/**
+ * Close a modal/overlay when the user presses Escape.
+ *
+ * Registers a document-level `keydown` listener so it works regardless
+ * of which element has focus. Every modal **must** use this hook —
+ * relying on `onKeyDown` on overlay divs is unreliable because those
+ * handlers only fire when the overlay itself (or a descendant) has focus.
+ *
+ * @param active  – whether the modal is currently open
+ * @param onClose – callback to close the modal
+ * @param options.capture – use capture phase (default: false).
+ *   Set to `true` for nested sub-modals that must intercept Escape
+ *   before a parent's handler fires.
+ */
+export function useEscapeKey(active: boolean, onClose: () => void, options?: { capture?: boolean }): void {
+	const capture = options?.capture ?? false;
+	const activeRef = useRef(active);
+	const onCloseRef = useRef(onClose);
+
+	// Keep refs in sync without re-registering the listener
+	activeRef.current = active;
+	onCloseRef.current = onClose;
+
+	useEffect(() => {
+		if (!active) return;
+		const handleKeyDown = (e: KeyboardEvent) => {
+			if (e.key === "Escape" && activeRef.current) {
+				onCloseRef.current();
+			}
+		};
+		document.addEventListener("keydown", handleKeyDown, capture);
+		return () => document.removeEventListener("keydown", handleKeyDown, capture);
+	}, [active, capture]);
+}