Terminal construction previously accepted GhosttyTerminalOptions with
dimensions and one scrollback byte limit. Remove the options struct from
the ABI and make ghostty_terminal_new accept columns and rows directly.
Add byte and line limit options to ghostty_terminal_set and forward them
to the runtime Terminal setters. NULL removes a limit, while zero bytes
disables scrollback. Update type metadata, tests, and all API examples.
The function previously took a size_t* out-parameter for the string
length. Since the JSON blob is now null-terminated, the len parameter
is unnecessary. Remove it from the Zig implementation, C header, and
the WASM example consumer which no longer needs to allocate and free
a usize just to read the length.
Replace hardcoded byte offsets and struct sizes with dynamic lookups
from the ghostty_type_json API. On WASM load, the type layout JSON
is fetched once and parsed into a lookup table. Two helpers,
fieldInfo and setField, use this metadata to write struct fields at
the correct offsets with the correct types.
This removes the need to manually maintain wasm32 struct layout
comments and magic numbers for GhosttyTerminalOptions and
GhosttyFormatterTerminalOptions, so the example stays correct if
the struct layouts change.
