fix(tui): proper Kitty image ID management and cleanup

- Add allocateImageId() to generate unique image IDs
- Add deleteKittyImage() and deleteAllKittyImages() functions
- Image component now tracks its ID and has dispose() method
- renderImage() returns imageId for tracking
- DOSBox: reuse single image ID for all frames, delete on dispose

Fixes image accumulation hitting terminal quota and lingering
images after component close.

packages/tui/src/index.ts

@@ -51,8 +51,11 @@ export { StdinBuffer, type StdinBufferEventMap, type StdinBufferOptions } from "
 export { ProcessTerminal, type Terminal } from "./terminal.js";
 // Terminal image support
 export {
+	allocateImageId,
 	type CellDimensions,
 	calculateImageRows,
+	deleteAllKittyImages,
+	deleteKittyImage,
 	detectCapabilities,
 	encodeITerm2,
 	encodeKitty,