chore: flatten src/ to root

ink/events/focus-event.ts

@@ -0,0 +1,21 @@
+import { type EventTarget, TerminalEvent } from './terminal-event.js'
+
+/**
+ * Focus event for component focus changes.
+ *
+ * Dispatched when focus moves between elements. 'focus' fires on the
+ * newly focused element, 'blur' fires on the previously focused one.
+ * Both bubble, matching react-dom's use of focusin/focusout semantics
+ * so parent components can observe descendant focus changes.
+ */
+export class FocusEvent extends TerminalEvent {
+  readonly relatedTarget: EventTarget | null
+
+  constructor(
+    type: 'focus' | 'blur',
+    relatedTarget: EventTarget | null = null,
+  ) {
+    super(type, { bubbles: true, cancelable: false })
+    this.relatedTarget = relatedTarget
+  }
+}