feat(cli): port ghostty +action CLI commands

Ports ZIG/src/cli into ghostty-cli: action detection/dispatch with
per-action --help, and the actions help, version, list-actions,
list-colors, list-keybinds, list-themes (plain listing plus an
interactive ratatui browser mirroring Ghostty's libvaxis UI),
show-config, validate-config, edit-config, crash-report (listing),
ssh-cache and boo (235 embedded frames).

Verified byte-for-byte against the installed Ghostty 1.3.1 for stdout,
stderr and exit codes of most actions, incl. tty output in a pty at
widths 20-200. Known differences: +list-colors --plain prints all 782
colors (Ghostty truncates at 617 because it never flushes), +version
has placeholder build info until build_info::set is wired up.

Deferred: list-fonts, show-face (need font discovery integration) and
new-window (needs GTK IPC); they return NotYetAvailable for now.

Test Plan:
- cargo test -p ghostty-cli (86 tests)
- cargo run -p ghostty-cli --example cli -- +list-keybinds --plain
  and diff against `ghostty +list-keybinds --plain`

crates/ghostty-cli/src/build_info.rs

@@ -0,0 +1,85 @@
+//! Build-time information shown by `+version` (Zig: `build_config`,
+//! `builtin`, `gtk_version`, `adw_version`).
+//!
+//! TODO(integration): the root crate / apprt-gtk should call [`set`] with the
+//! real GTK and libadwaita versions (the Zig code queries them at runtime).
+
+use std::sync::OnceLock;
+
+/// A `major.minor.micro` version (Zig: `gtk_version.zig` / `adw_version.zig`).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Version {
+    pub major: u32,
+    pub minor: u32,
+    pub micro: u32,
+}
+
+impl std::fmt::Display for Version {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}.{}.{}", self.major, self.minor, self.micro)
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct BuildInfo {
+    /// `build_config.version_string`.
+    pub version_string: String,
+    /// `build_config.version.build` (the git commit hash), if known.
+    pub commit: Option<String>,
+    /// `build_config.release_channel` tag name (`stable` / `tip`).
+    pub release_channel: String,
+    /// `{}` of `builtin.mode` (`.Debug`, `.ReleaseFast`, ...).
+    pub build_mode: String,
+    /// `{}` of `build_config.app_runtime`.
+    pub app_runtime: String,
+    /// `{}` of `build_config.font_backend`.
+    pub font_backend: String,
+    /// `{}` of `renderer.Renderer`.
+    pub renderer: String,
+    pub gtk_build: Option<Version>,
+    pub gtk_runtime: Option<Version>,
+    pub adw_build: Option<Version>,
+    pub adw_runtime: Option<Version>,
+    /// `build_options.x11`.
+    pub x11: bool,
+    /// `build_options.wayland`.
+    pub wayland: bool,
+}
+
+impl Default for BuildInfo {
+    fn default() -> Self {
+        BuildInfo {
+            version_string: "1.3.1".to_string(),
+            commit: None,
+            release_channel: "stable".to_string(),
+            build_mode: if cfg!(debug_assertions) {
+                ".Debug"
+            } else {
+                ".ReleaseFast"
+            }
+            .to_string(),
+            app_runtime: ".gtk".to_string(),
+            font_backend: ".fontconfig_freetype".to_string(),
+            renderer: "renderer.generic.Renderer(renderer.OpenGL)".to_string(),
+            gtk_build: None,
+            gtk_runtime: None,
+            adw_build: None,
+            adw_runtime: None,
+            x11: true,
+            wayland: true,
+        }
+    }
+}
+
+static INFO: OnceLock<BuildInfo> = OnceLock::new();
+
+/// Install the build info. Returns false if it was already set.
+pub fn set(info: BuildInfo) -> bool {
+    INFO.set(info).is_ok()
+}
+
+/// The installed build info, or the defaults.
+#[must_use]
+pub fn get() -> BuildInfo {
+    INFO.get().cloned().unwrap_or_default()
+}