[POC] Add PrintOptions destination to Print API

[aaronschubert0]

Summary

• Add PrintDestination type ('system' | 'receipt') and PrintOptions interface to the Print API
• Update PrintApiContent.print() method signature to accept an optional PrintOptions second parameter: print(src: string, options?: PrintOptions): Promise<void>
• Export new types from the POS surface barrel file (api.ts)
• Update print-api.doc.ts to include PrintOptions and PrintDestination in the generated documentation definitions

Why

Extensions currently cannot print to the physical receipt printer connected to a POS device. This adds a destination option to the existing Print API so extensions can choose between the system print dialog (default) and the receipt printer.

The design follows the Web API alignment pattern (Window.print() extended with an options-bag, like fetch(url, options)), making the change backward-compatible — the second parameter is optional and defaults to 'system' behavior.

Type Changes

/** The target destination for printing. */
export type PrintDestination = 'system' | 'receipt';

export interface PrintOptions {
  /** @defaultValue 'system' */
  destination?: PrintDestination;
}

export interface PrintApiContent {
  print(src: string, options?: PrintOptions): Promise<void>;
}

Test plan

• TypeScript compiles cleanly (tsc --project packages/ui-extensions/tsconfig.json passes)
• Verify generated docs include PrintOptions and PrintDestination types
• Backward-compatible: existing print(src) calls without options continue to work

🤖 Generated with Claude Code