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`

docs/rewrite/notes/ghostty-cli.md

@@ -0,0 +1,87 @@
+# ghostty-cli port notes (C1)
+
+Crate `crates/ghostty-cli` (deps: ghostty-config, ghostty-input, ghostty-os; plus
+ratatui/crossterm for TUIs, flate2 for boo frames, unicode-width). Run end to end with
+`cargo run -p ghostty-cli --example cli -- +list-actions --docs` (the example behaves
+like `ghostty` for actions via `ghostty_cli::run_from_args`, which also reproduces
+main_ghostty.zig's "multiple/unknown action" errors). Do not edit the root crate:
+wire `run_from_args(&std::env::args().collect::<Vec<_>>())` into its main later.
+
+## API
+Every action module exposes `pub fn run(args: &[String]) -> Result<u8, Error>`; `args` is the
+full argv (argv[0] skipped, `+action` args ignored, like `args.argsIterator`). `--help`/`-h`
+yields `Error::ActionHelpRequested`, which `Action::run` turns into the help text (stdout, exit 0).
+`Action::{ALL,name,from_name,file,help_text,run}`, `action::{detect_iter,ActionEnum,SpecialCase}`.
+
+## File -> module
+| Zig | Rust |
+|---|---|
+| cli.zig / action.zig | `action.rs` (generic detection + 7 tests) |
+| ghostty.zig | `ghostty.rs` (`Action`, dispatch, help, `run_from_args`; 5 tests) |
+| help.zig, version.zig | `help.rs`, `version.rs` (+ `build_info.rs`) |
+| list_actions/list_colors/list_keybinds | same names; pretty output via `tui.rs` |
+| list_themes.zig | `list_themes.rs` (listing) + `list_themes/preview.rs` (ratatui TUI) |
+| show_config/validate_config/edit_config/crash_report | same names |
+| ssh_cache.zig + ssh-cache/{Entry,DiskCache} | `ssh_cache.rs`, `ssh_cache/{entry,disk_cache}.rs` |
+| boo.zig (+ build/framegen/frames) | `boo.rs`, `boo_frames.deflate` (235 frames, raw deflate of frames joined by \x01) |
+| tui.zig | `tui.rs` (+ a small vaxis `prettyPrint` clone) |
+| list_fonts/show_face/new_window | stubs: Options + help + `Error::NotYetAvailable` (TODO(integration)) |
+
+Help texts (`help/*.txt`) are the `run` doc comments of the Zig files, extracted with the
+helpgen rules (common-indent strip); `--help` output is byte-identical to Ghostty 1.3.1.
+
+## Oracle verification (Ghostty 1.3.1 at /usr/bin/ghostty)
+Byte-identical (stdout, stderr, exit code): `+list-actions` (+`--docs`, `--help`), `+list-keybinds`
+(`--plain`, `--default`, `--docs`; also with a custom config containing chords, chains, tables,
+catch_all, unicode keys), `+list-themes --plain` (`--path`, `--color=dark|light`; with
+`GHOSTTY_RESOURCES_DIR=/usr/share/ghostty`), `+help`, `--help`, `-h`, `+validate-config` (ok and
+missing file), `+crash-report`, `+ssh-cache`, bad action / multiple actions / bad flag errors,
+`--help` of every action, `+show-config` (except the two known config deviations: `auto-update-channel`
+tip vs stable, `gtk-opengl-debug` debug build). **Pretty (tty) output of `+list-colors` and
+`+list-keybinds` is byte-identical in a pty** for widths 20..200 (including line wrapping and
+the first-row/teardown sequences of libvaxis); verified with a pty harness.
+
+Known differences:
+* `+list-colors --plain`: Ghostty 1.3.1 never flushes its 4 KiB stdout buffer on this path, so its
+  output is truncated at 617 of 782 lines. We print all 782 (first 617 identical).
+* `+list-colors` in a tty narrower than one column: Zig divides by zero; we clamp to one column.
+* `+version` differs in version/build info (placeholders in `build_info`; TODO(integration): root
+  crate / apprt-gtk should call `build_info::set` with the real GTK/libadwaita versions, commit
+  and channel). "Zig version" row became "Rust version", "libxev" row prints `n/a`.
+* `+edit-config` exec failure prints `error.FileNotFound`/`error.AccessDenied` for those kinds,
+  otherwise the Rust io error text.
+* `+new-window`: the Zig parse hook swallows `--help`; ported as is. IPC not available.
+
+## Interactive `+list-themes` (ratatui)
+Same layout as the vaxis version: 32-column list with `❯ name ❮` selection, preview (header, 16
+color swatches with decimal/hex numbers, 24-line code sample, lorem ipsum filler, diagnostics /
+load-error panels), help (60x22), search (3-high box at bottom) and save (92x17) overlays, all
+key bindings (q/Esc/^C, ?/F1/^H, /, ^X ^/, j/k/arrows, PgUp/PgDn (20), Home/End, h/x/d hex
+toggle, c / C copy name/path via OSC 52, f cycle filter, Enter save dialog, w write
+`auto/theme.ghostty`), mouse wheel / click / hover. Differences: no OSC 8 hyperlinks on names,
+double/dashed/dotted/curly underlines drawn as single, color scheme not queried live (defaults to
+light like Zig; `COLORFGBG` used as a hint), theme load errors during filtering are ignored
+(Zig aborts), `zf` fuzzy ranking replaced by a subsequence matcher (only matching, not order, is
+used). Logic (filtering, navigation, windowing, search, save) is unit tested; rendering is tested
+against a ratatui `Buffer`.
+
+## Tests
+Ported every Zig test in the ported files: action.zig (7 detect tests), ghostty.zig (5 parse
+action tests), ssh-cache/Entry.zig (6), DiskCache.zig (4 operation tests + isValidHost,
+isValidUser, isValidCacheKey). Skipped: none. 86 tests total including new ones (help/version
+output, show-config, validate-config, crash-report, ssh-cache action, list-colors/keybinds/themes,
+tui row rendering vs vaxis bytes, boo frame parsing of all 235 frames, preview state machine,
+new-window arg hook).
+
+## TODO(integration) / gaps
+* `list-fonts`, `show-face` (need ghostty-font), `new-window` (GTK IPC): return `Error::NotYetAvailable`.
+* `build_info::set` for real version/GTK info.
+* ghostty-vt `x11_color` lacks a key listing and loses name case: `list_colors` re-parses
+  `ghostty-vt/src/res/rgb.txt` through a relative `include_str!` path.
+* ghostty-input `ActionKey::docs()` has an extra trailing blank line for 4 actions
+  (adjust_selection, ...) compared to Ghostty's help strings; `list_actions::generate_plaintext`
+  is a local copy of `helpgen_actions::generate` that normalises trailing newlines. Fix the data in
+  ghostty-input and switch back to `helpgen_actions::generate`.
+* crash-report only lists (sentry is not ported). `ssh-cache` locking uses `File::try_lock`;
+  like Zig, a lock held by another process is ignored (the boolean result is unused upstream).
+* `Config::load` and `finalize` are called twice in `validate-config` (as in Zig).