Keybinds (fork C)

Config.Keybinds -> crates/ghostty-config/src/keybinds.rs.
Struct: set: Set, tables: Vec<(String, Set)> (insertion ordered), chain_target: ChainTarget.
init() = Linux/GTK default table only (darwin branches dropped), same insertion order as Zig.
ConfigField: parse_cli (clear, empty -> init, name/ tables, chain= target tracking), reset -> init(), format_entry / format_entry_docs.
PartialEq follows Zig equal/equalSet (ignores reverse map and chain state).
Formatting uses ghostty_input::binding::set::Value::format_entries through an adapter to EntryFormatter.
Errors from input's binding::Error map to ArgError::Other("InvalidFormat"|"InvalidAction").
Tests: 31 ported/added (all Zig tests in range ported, 0 skipped; plus reset_calls_init, default_keybinds_format_roundtrip).

Quirks

format_entry_docs(docs=true): Zig looks up help via @tagName(v) of the set Value (leader/leaf/leaf_chained), which never matches a keybind action, so only a blank line is emitted. Preserved.
Keybinds::default() is EMPTY (Zig .{}); Config::default must call init().
Input's Set has no PartialEq; equality is implemented locally.