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/list-fonts.txt

@@ -0,0 +1,24 @@
+The `list-fonts` command is used to list all the available fonts for
+Ghostty. This uses the exact same font discovery mechanism Ghostty uses to
+find fonts to use.
+
+When executed with no arguments, this will list all available fonts, sorted
+by family name, then font name. If a family name is given with `--family`,
+the sorting will be disabled and the results instead will be shown in the
+same priority order Ghostty would use to pick a font.
+
+Flags:
+
+  * `--bold`: Filter results to specific bold styles. It is not guaranteed
+    that only those styles are returned. They are only prioritized.
+
+  * `--italic`: Filter results to specific italic styles. It is not guaranteed
+    that only those styles are returned. They are only prioritized.
+
+  * `--style`: Filter results based on the style string advertised by a font.
+    It is not guaranteed that only those styles are returned. They are only
+    prioritized.
+
+  * `--family`: Filter results to a specific font family. The family handling
+    is identical to the `font-family` set of Ghostty configuration values, so
+    this can be used to debug why your desired font may not be loading.