chrome: greatly improve soft-keyboard visibility & layout handling

This reworks how we detect and respond to the on-screen keyboard so inputs
don’t get buried and the UI doesn’t “jump”.

- Add SoftKeyboardAnim + AnimState FSM for smooth IME open/close animation
- Centralize logic in keyboard_visibility() with clear edge states
- Animate keyboard height via animate_value_with_time instead of layer
  transforms
- Add ChromeOptions::KeyboardVisibility flag when focused input would be
  occluded
- Add SidebarOptions::Compact to collapse sidebar while typing
- Hide mobile toolbar when keyboard is open (columns app)
- Use .stick_to_bottom(true) in reply + profile editors; remove old spacer hack
- Virtual keyboard toggle moved to F1 in Debug builds
- Introduce SoftKeyboardContext::platform(ctx) helper
- Cleanup dead/commented code and wire up soft_kb_anim_state in Chrome

Result: inputs stay visible, open/close is smooth, and UI adjusts gracefully
when typing.

Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck/src/context.rs

@@ -40,6 +40,14 @@ pub enum SoftKeyboardContext {
     Platform { ppp: f32 },
 }
 
+impl SoftKeyboardContext {
+    pub fn platform(context: &egui::Context) -> Self {
+        Self::Platform {
+            ppp: context.pixels_per_point(),
+        }
+    }
+}
+
 impl<'a> AppContext<'a> {
     pub fn soft_keyboard_rect(&self, screen_rect: Rect, ctx: SoftKeyboardContext) -> Option<Rect> {
         match ctx {
@@ -53,8 +61,13 @@ impl<'a> AppContext<'a> {
                 #[cfg(target_os = "android")]
                 {
                     use android_activity::InsetType;
+
+                    // not sure why I need this, it seems to be consistently off by some amount of
+                    // pixels ?
+                    let fudge = 0.0;
+
                     let inset = self.android.get_window_insets(InsetType::Ime);
-                    let height = inset.bottom as f32 / ppp;
+                    let height = (inset.bottom as f32 / ppp) - fudge;
                     skb_rect_from_screen_rect(screen_rect, height)
                 }