refactor: split every monolithic module into focused submodules

Each source file that had grown beyond a single concern is replaced by an identically-named directory containing focused submodules. `src/event_loop/mod.rs` (878 lines) becomes a directory with clipboard, context_menu, cursor_shape, drag, focus, handlers, invalidation, overlays_reconcile, repeat, run, surface, text_editing, and tooltip. Every widget, input handler, and theme component follows the same split. Public interfaces are unchanged — only the internal file layout moves.
image bumped from 0.25.2 to 0.25.9.

src/draw/mod.rs

@@ -114,7 +114,7 @@ pub( crate ) struct DrawCtx<Msg: Clone>
 /// toolkit follows for runtime-internal popups.
 pub( crate ) fn draw_context_menu(
 	canvas: &mut crate::render::Canvas,
-	menu:   &crate::event_loop::app_data::ContextMenu,
+	menu:   &crate::event_loop::context_menu::ContextMenu,
 )
 {
 	let palette = crate::theme::palette();