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.

tests/common/mod.rs

@@ -22,6 +22,7 @@ pub fn lw_none( flat_idx: usize, rect: Rect ) -> LaidOutWidget<()>
 		handlers:           WidgetHandlers::None,
 		keyboard_focusable: true,
 		cursor:             CursorShape::Default,
+		tooltip:            None,
 	}
 }
 
@@ -37,6 +38,7 @@ pub fn lw_button( flat_idx: usize, rect: Rect ) -> LaidOutWidget<()>
 		handlers:           WidgetHandlers::Button { on_press: Some( () ), on_long_press: None, on_drag_start: None, on_escape: None, repeating: false },
 		keyboard_focusable: true,
 		cursor:             CursorShape::Pointer,
+		tooltip:            None,
 	}
 }
 
@@ -54,6 +56,7 @@ pub fn lw_chrome( flat_idx: usize, rect: Rect ) -> LaidOutWidget<()>
 		handlers:           WidgetHandlers::WindowButton { on_press: Some( () ) },
 		keyboard_focusable: false,
 		cursor:             CursorShape::Pointer,
+		tooltip:            None,
 	}
 }