Follow up to #13978
`ghostty_terminal_paste` no longer takes the clipboard's data up front.
The request now carries only the list of available MIME types plus a
a callback that writes one representation's bytes into a `GhosttyWriter`.
Previously an embedder had to load every representation for every MIME
type into memory before pasting. For a clipboard holding a large image
or video next to some text that could be hundreds of megabytes that
were never used.
I also took care to make sure that the data is only read once, to avoid
any time-of-check/time-of-use (TOCTOU) issues.
There is only one case where data might be fully buffered in memory now:
unsafe text data that needs to be checked. This is true for how Ghostty
GUI works today too.
Add ghostty_paste_encode() which encodes paste data for writing to
the terminal pty. It strips unsafe control bytes, wraps in bracketed
paste sequences when requested, and replaces newlines with carriage
returns for unbracketed mode. The input buffer is modified in place
and the encoded result is written to a caller-provided output buffer,
following the same buffer/out_written pattern as the other encode
functions like ghostty_size_report_encode.
Update the c-vt-paste example with an encode_example() demonstrating
the new function and add corresponding @snippet references in the
header documentation.
