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/help/new-window.txt

@@ -0,0 +1,62 @@
+The `new-window` will use native platform IPC to open up a new window in a
+running instance of Ghostty.
+
+If the `--class` flag is not set, the `new-window` command will try and
+connect to a running instance of Ghostty based on what optimizations the
+Ghostty CLI was compiled with. Otherwise the `new-window` command will try
+and contact a running Ghostty instance that was configured with the same
+`class` as was given on the command line.
+
+All of the arguments after the `+new-window` argument (except for the
+`--class` flag) will be sent to the remote Ghostty instance and will be
+parsed as command line flags. These flags will override certain settings
+when creating the first surface in the new window. Currently, only
+`--working-directory`, `--command`, and `--title` are supported. `-e` will
+also work as an alias for `--command`, except that if `-e` is found on the
+command line all following arguments will become part of the command and no
+more arguments will be parsed for configuration settings.
+
+If `--working-directory` is found on the command line and is a relative
+path (i.e. doesn't start with `/`) it will be resolved to an absolute path
+relative to the current working directory that the `ghostty +new-window`
+command is run from. `~/` prefixes will also be expanded to the user's home
+directory.
+
+If `--working-directory` is _not_ found on the command line, the working
+directory that `ghostty +new-window` is run from will be passed to Ghostty.
+
+GTK uses an application ID to identify instances of applications. If Ghostty
+is compiled with release optimizations, the default application ID will be
+`com.mitchellh.ghostty`. If Ghostty is compiled with debug optimizations,
+the default application ID will be `com.mitchellh.ghostty-debug`.  The
+`class` configuration entry can be used to set up a custom application
+ID. The class name must follow the requirements defined [in the GTK
+documentation](https://docs.gtk.org/gio/type_func.Application.id_is_valid.html)
+or it will be ignored and Ghostty will use the default as defined above.
+
+On GTK, D-Bus activation must be properly configured. Ghostty does not need
+to be running for this to open a new window, making it suitable for binding
+to keys in your window manager (if other methods for configuring global
+shortcuts are unavailable). D-Bus will handle launching a new instance
+of Ghostty if it is not already running. See the Ghostty website for
+information on properly configuring D-Bus activation.
+
+Only supported on GTK.
+
+Flags:
+
+  * `--class=<class>`: If set, open up a new window in a custom instance of
+    Ghostty. The class must be a valid GTK application ID.
+
+  * `--command`: The command to be executed in the first surface of the new window.
+
+  * `--working-directory=<directory>`: The working directory to pass to Ghostty.
+
+  * `--title`: A title that will override the title of the first surface in
+    the new window. The title override may be edited or removed later.
+
+  * `-e`: Any arguments after this will be interpreted as a command to
+    execute inside the first surface of the new window instead of the
+    default command.
+
+Available since: 1.2.0