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/widget/window_button/theme.rs

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: LGPL-2.1-only
+// Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>
+
+use crate::types::Color;
+
+pub fn icon()        -> Color { crate::theme::window_controls().icon           }
+pub fn hover_bg()    -> Color { crate::theme::window_controls().hover_bg       }
+pub fn pressed_bg()  -> Color { crate::theme::window_controls().pressed_bg     }
+pub fn focus_color() -> Color { crate::theme::window_controls().focus_ring     }
+pub fn close_hover() -> Color { crate::theme::window_controls().close_hover_bg }
+pub fn close_icon()  -> Color { crate::theme::window_controls().close_icon     }
+
+pub const SIZE:     f32 = 36.0;
+pub const RADIUS:   f32 = 10.0;
+pub const FOCUS_W:  f32 = 2.0;
+pub const STROKE_W: f32 = 2.0;