kitty graphics support

[BYK]

We added sixel-based rendering but apparently the newer terminals prefer the kitty protocol. We should definitely support this newer one and we can consider dropping sixel if its support is not as widespread or there's enough overlap.

[MathurAditya724]

@jared-outpost please pick this up now. Investigate kitty graphics support, implement the smallest defensible fix, add focused validation, self-review, and open a scoped PR. Report a blocker only if you cannot establish a safe path.

[jared-outpost]

already in flight — PR #1484 implements kitty graphics support: the terminal probe now detects the kitty protocol (a=q query) and sentry api renders image attachments via kitty when available, falling back to sixel on older terminals. sixel is kept as the fallback rather than dropped, since it's the only option on terminals that don't speak kitty.

it's out of draft, CI is green, and review feedback from bugbot/sentry has been addressed (kitty-only pixel-width budget + banner respecting defaults graphics off, latest fix in 5a82414). waiting on @BYK to review.