feat(core): port App/Surface and wire up the runnable ghostty binary

This is the integration step that turns the ported crates into a working
terminal: `cargo run` now opens a GTK window running the user's shell.

ghostty-core ports App.zig, Surface.zig (split into keyboard, mouse,
binding, clipboard and config submodules), surface_mouse.zig and
global.zig, and implements the runtime traits. perform_binding_action
handles every binding action.

Cross-crate integration:
- The core<->runtime traits (CoreApp, CoreSurface, RtApp, RtSurface,
  Waker) move from apprt-gtk into ghostty_apprt::runtime_api so the core
  stays runtime-agnostic; Scrollbar/RendererHealth stand-ins are replaced
  by the real terminal/renderer types.
- termio now uses ghostty_renderer::state::{State, SharedState}; the
  renderer calls kitty_update; image-storage-limit is applied at init
  and on config change.
- The search thread locks the terminal through a TerminalLock trait so
  it can share the render state mutex; termio's Wakeup gained a hook to
  wake the renderer thread.
- apprt-gtk: GL proc addresses are resolved through libepoxy's
  epoxy_glFoo pointer variables (plain glFoo symbols resolved to null),
  default DPI fixed to 96, libadwaita version read without GTK init so
  --version works headless.

The root binary dispatches +actions to ghostty-cli (list-fonts,
show-face and new-window are now wired) and otherwise runs the GTK app
with the real core.

Verified at runtime on Wayland and X11: shell prompt and colored output
render, child exit closes the window cleanly. Not yet verified: keyboard
and mouse input, clipboard, IME, tabs and splits (no key injection was
possible in this environment). GHOSTTY_DEBUG_SCREENSHOT=<png> dumps the
renderer's last frame for headless checks.

Test Plan:
- cargo test --workspace (2890 passed)
- cargo clippy --workspace --all-targets -- -D warnings
- GSETTINGS_BACKEND=memory GHOSTTY_RESOURCES_DIR=/usr/share/ghostty \
  cargo run

crates/ghostty-renderer/src/generic.rs

@@ -1886,16 +1886,11 @@ fn update_kitty(
     terminal: &mut ghostty_terminal::terminal::Terminal,
     cell_size: CellSize,
 ) {
-    // TODO(integration): `Screen.kitty_images` is still the placeholder
-    // `KittyImages { dirty }` (see docs/rewrite/notes/ghostty-terminal-kitty.md).
-    // Once it is a `kitty::ImageStorage`, call
-    //   images.kitty_update(&screen.kitty_images, &screen.pages,
-    //       &TerminalInfo::from_terminal(terminal), cell_size);
-    // and then clear `screen.kitty_images.dirty`. `image::State::kitty_update`
-    // is implemented and compiled against the real storage API already.
-    let _ = cell_size;
+    let info = ghostty_terminal::kitty::graphics_storage::TerminalInfo::from_terminal(terminal);
+    let screen = terminal.screen_mut();
+    images.kitty_update(&screen.kitty_images, &screen.pages, &info, cell_size);
     images.force_kitty_update = false;
-    terminal.screen_mut().kitty_images.dirty = false;
+    screen.kitty_images.dirty = false;
 }
 
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