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/input/repeat/mod.rs

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-only
+// Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>
+
+pub( crate ) mod key;
+pub( crate ) mod button;