feat(dist): generate completions, editor syntax, man pages, translations

Ports Ghostty's build-data helpers (main_build_data.zig, src/extra/*,
build/mdgen) as the ghostty-build-data binary: bash/zsh/fish
completions, Vim syntax/ftdetect/ftplugin/compiler, Sublime syntax (also
used by bat), terminfo source and ghostty(1)/ghostty(5) markdown. With
the version set to the installed 1.3.1-arch2, all generated files are
byte-identical to the installed Ghostty's.

- `just docs` renders man pages and HTML with pandoc.
- po/: Ghostty's 29 translation catalogs; `just locales` compiles them
  into the com.mitchellh.ghostty gettext domain.
- `just install PREFIX FLATPAK SYSTEM_PACKAGE` installs everything incl.
  terminfo text/termcap outputs and mirrors GhosttyResources.zig install
  modes (Flatpak D-Bus template without systemd; lib/systemd/user for
  system packages).
- Build metadata (version, tip/stable channel, commit, build mode) is
  derived at build time like build_config.zig; GTK/libadwaita
  compile-time versions come from pkg-config instead of constants.

Test Plan:
- cargo run -p ghostty-build-data -- +bash | diff - \
  /usr/share/bash-completion/completions/ghostty (same for zsh/fish/vim)
- just install /tmp/prefix

crates/ghostty-build-data/src/zsh.rs

@@ -0,0 +1,95 @@
+//! Zsh completions (port of `extra/zsh.zig`).
+
+use std::fmt::Write as _;
+
+use ghostty_config::cli_args::FieldKind;
+
+use crate::chunks_zsh::{C0, C1, C2, C3};
+use crate::{actions, config_fields, join_names, join_packed};
+
+const EQUALS_REQUIRED: &str = "=-:::";
+
+#[must_use]
+pub fn completions() -> String {
+    let mut w = String::new();
+    w.push_str(C0);
+    w.push_str("_config() {\n");
+    w.push_str("  _arguments \\\n");
+    w.push_str("    \"--help\" \\\n");
+    w.push_str("    \"--version\" \\\n");
+    for f in config_fields() {
+        let _ = write!(w, "    \"--{}", f.name);
+        if f.name.starts_with("font-family") {
+            let _ = write!(w, "{EQUALS_REQUIRED}_fonts");
+        } else if f.name == "theme" {
+            let _ = write!(w, "{EQUALS_REQUIRED}_themes");
+        } else if f.name == "working-directory" {
+            let _ = write!(w, "{EQUALS_REQUIRED}{{_files -/}}");
+        } else if f.kind == FieldKind::RepeatablePath {
+            let _ = write!(w, "{EQUALS_REQUIRED}_files");
+        } else {
+            match f.kind {
+                FieldKind::Bool => {}
+                FieldKind::Enum(names) => {
+                    let _ = write!(w, "{EQUALS_REQUIRED}({})", join_names(names));
+                }
+                FieldKind::Packed(names) => {
+                    let _ = write!(w, "{EQUALS_REQUIRED}({})", join_packed(names));
+                }
+                _ => {
+                    let _ = write!(w, "{EQUALS_REQUIRED}( )");
+                }
+            }
+        }
+        w.push_str("\" \\\n");
+    }
+    w.push_str("\n}\n\n");
+
+    w.push_str(C1);
+    let padding = "        ";
+    for a in actions() {
+        let _ = writeln!(w, "{padding}'+{}'", a.name());
+    }
+    w.push_str(C2);
+
+    for a in actions() {
+        let opts = a.option_fields();
+        if opts.is_empty() {
+            continue;
+        }
+        let _ = writeln!(w, "{padding}(+{})", a.name());
+        let _ = writeln!(w, "{padding}  _arguments \\");
+        for (name, kind) in &opts {
+            let _ = write!(w, "{padding}    '--{name}");
+            match kind {
+                FieldKind::Bool => {}
+                FieldKind::Enum(names) => {
+                    let _ = write!(w, "{EQUALS_REQUIRED}({})", join_names(names));
+                }
+                FieldKind::OptionalEnum(names) => {
+                    let _ = write!(w, "{EQUALS_REQUIRED}({})", join_names(names));
+                }
+                FieldKind::OptionalBool | FieldKind::OptionalOther => {
+                    w.push_str(EQUALS_REQUIRED);
+                    if *name == "config-file" {
+                        w.push_str("_files");
+                    } else {
+                        w.push_str("( )");
+                    }
+                }
+                _ => {
+                    w.push_str(EQUALS_REQUIRED);
+                    if *name == "config-file" {
+                        w.push_str("_files");
+                    } else {
+                        w.push_str("( )");
+                    }
+                }
+            }
+            w.push_str("' \\\n");
+        }
+        let _ = writeln!(w, "{padding};;");
+    }
+    w.push_str(C3);
+    w
+}