Resolves#8689
For various reason, ghostty wants to have a unique file extension for
the config files. The name was settled on `config.ghostty`. This will
help with tooling. See #8438 (original discussion) for more details.
This PR introduces the preferred default of `.ghostty` while still
supporting the previous `config` file. If both files exist, a warning
log is sent.
The docs / website will need to be updated to reflect this change.
> [!NOTE]
> Only tested on macOS 26.0.
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Co-authored-by: Mitchell Hashimoto <m@mitchellh.com>
cbeb6890c9