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/theme/typography.rs

@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: LGPL-2.1-only
+// Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>
+
+//! Typography scale used by the default theme.
+//!
+//! Designed around the **Sora** typeface (Google Fonts). If Sora is not
+//! installed on the system, ltk falls back to Liberation Sans / DejaVu Sans;
+//! glyph metrics will differ slightly but the scale still reads correctly.
+
+pub const H0:       f32 = 50.0;
+pub const H1:       f32 = 34.0;
+pub const H2:       f32 = 24.0;
+pub const H3:       f32 = 20.0;
+pub const BODY:     f32 = 16.0;
+pub const BODY_S:   f32 = 14.0;
+pub const BODY_XS:  f32 = 12.0;
+
+/// Interlineado (line-height) multiplier recommended by the kit. Apply as
+/// `size * LINE_HEIGHT` when laying out multi-line text blocks.
+pub const LINE_HEIGHT: f32 = 1.5;