yoda: iced_winit dead-code purge (29→0 warnings)

Removed code paths inherited from past refactors that no longer have any
reader:

- ViewFn type alias (window.rs)
- a11y_enabled flag and resized flag (lib.rs) — assigned but never read
- BootConfig.fonts/graphics_settings/is_wayland — already passed to
  run_instance(...) directly; the BootConfig copies were never read
- Runner.system_theme oneshot::Sender — stored but no producer ever
  wired; receiver side already falls back to default
- event_loop/control_flow.rs — local ControlFlow enum, all callers use
  winit::event_loop::ControlFlow
- event_loop/proxy.rs — Proxy<Message> never constructed
- Error::Connect(ConnectError) variant — never constructed
- Common.has_focus / ime_pos / ime_size — never read after assignment
- SctkPopupData.grab — replicated settings.grab, never read back
- SubsurfaceEventVariant::Created.surface field — destructure does
  `surface: _` everywhere, the value is unused

Visibility tightening:
- a11y.rs WinitActivationHandler / WinitActionHandler /
  WinitDeactivationHandler: pub proxy → pub(crate) proxy
- conversion::touch_event: pub → private (no external callers)
- proxy::Proxy:🆕 pub → pub(crate)

Allow attributes (intentional, not warning-suppression):
- conversion::RawImage: #[allow(dead_code)] — fields kept for
  IconProvider downcast-via-AsAny on winit's side
- event_loop::Error: #[allow(dead_code)] — variant payloads kept for
  Debug, never inspected programmatically
- lib.rs Event<Message>: #[allow(hidden_glob_reexports)] — intentional
  shadow of winit::event::Event coming from `pub use winit`
- window.rs/lib.rs: #[allow(deprecated)] on enable_ime/disable_ime/
  process_event with TODOs for set_ime_* → request_ime_update and
  try_next → try_recv migrations

Five orphan imports also removed (Hash/Hasher, BorrowMut, 3× Compositor).

Leyoda 2026 – GPLv3

winit/src/a11y.rs

@@ -7,7 +7,7 @@ use iced_accessibility::accesskit::{
 use iced_runtime::core;
 
 pub struct WinitActivationHandler {
-    pub proxy: mpsc::UnboundedSender<Control>,
+    pub(crate) proxy: mpsc::UnboundedSender<Control>,
     pub title: String,
 }
 
@@ -33,7 +33,7 @@ impl ActivationHandler for WinitActivationHandler {
 
 pub struct WinitActionHandler {
     pub id: core::window::Id,
-    pub proxy: mpsc::UnboundedSender<Control>,
+    pub(crate) proxy: mpsc::UnboundedSender<Control>,
 }
 
 impl iced_accessibility::accesskit::ActionHandler for WinitActionHandler {
@@ -48,7 +48,7 @@ impl iced_accessibility::accesskit::ActionHandler for WinitActionHandler {
 }
 
 pub struct WinitDeactivationHandler {
-    pub proxy: mpsc::UnboundedSender<Control>,
+    pub(crate) proxy: mpsc::UnboundedSender<Control>,
 }
 
 impl iced_accessibility::accesskit::DeactivationHandler