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/date_picker/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 surface()        -> Color { crate::theme::palette().surface }
+pub fn surface_alt()    -> Color { crate::theme::palette().surface_alt }
+pub fn text()           -> Color { crate::theme::palette().text_primary }
+pub fn text_muted()     -> Color { crate::theme::palette().text_secondary }
+pub fn accent()         -> Color { crate::theme::palette().accent }
+pub const PADDING:    f32 = 16.0;
+pub const RADIUS:     f32 = 16.0;
+pub const HEADER_FS:  f32 = 16.0;
+pub const DOW_FS:     f32 = 12.0;
+pub const DAY_FS:     f32 = 14.0;
+pub const CELL_SIZE:  f32 = 36.0;
+pub const SPACING:    f32 = 4.0;