Terminal can now render inline images (kitty graphics protocol)

What

• Terminal capability detection now checks for kitty graphics protocol support (a new kittyGraphics capability, alongside kittyKeyboard/synchronizedOutput/extendedKeys), matching the terminal name against a kitty/ghostty allowlist and minimum version; it's off by default inside tmux/screen and disabled entirely for background workers, but can be forced on with an environment variable.
• A new Image content type was added alongside existing block types like Markdown and Raster, so images can appear as their own block wherever those are rendered.
• Images can be sent as PNG data or raw RGBA pixel data, with validation of the data's format (base64 padding, PNG signature/header), byte size against width and height, and overall prop shape.
• The terminal renderer tracks when on-screen images go stale (e.g. after a screen reset, alternate-screen toggle, or focus reset) and retransmits/redraws them so they don't disappear or look broken after a redraw.
• A byte-size cap was added so a UI element tree is rejected once the combined size of its images exceeds a threshold.

Why

Previously the terminal could only show text; on terminals that support it, Claude Code can now display real inline images (for example, screenshots or generated pictures) directly in the session, while guarding against oversized image payloads and stale or broken redraws.