#13182
Replace the OSC 52-specific kind and encoded payload callback with an
atomic clipboard write containing a normalized destination and decoded
MIME representations. This keeps protocol details out of embedders and
lets iTerm2 Copy use the same semantic path.
Represent clears with an empty content list, preserve binary payloads,
and return a generic result for protocols that acknowledge writes. Add
the C ABI descriptors, layout metadata, and effects example so future
multipart protocols can reuse the callback without another API break.
Previously ghostty_terminal_set required all values to be passed as
pointers to the value, even when the value itself was already a
pointer (userdata, function pointer callbacks). This forced callers
into awkward patterns like compound literals or intermediate
variables just to take the address of a pointer.
Now pointer-typed options (userdata and all callbacks) are passed
directly as the value parameter. Only non-pointer types like
GhosttyString still require a pointer to the value. This
simplifies InType to return the actual stored type for each option
and lets setTyped work with those types directly.
Add a comprehensive "Effects" section to the terminal module
documentation in terminal.h explaining the callback system that
lets embedding applications react to terminal-initiated events
(bell, title changes, pty writes, device queries, etc.). The
section includes a reference table of all available effects and
their triggers, plus @snippet references to the new example.
Add c-vt-effects example project demonstrating how to register
write_pty, bell, and title_changed callbacks, attach userdata,
and feed VT data that triggers each effect.
