Fix #676.

The latest pptxgenjs has improved support for hybrid environments, such as Web, Node.js, and other bundlers. If pptxgenjs detected running on Node.js, pptxgenjs will try to import node:fs and node:https dynamically with import statement.

// STEP 2: Lazy-load Node built-ins if needed
const loadNodeDeps = isNode
  ? async () => {
    ; ({ default: fs } = await import('node:fs')); ({ default: https } = await import('node:https'))
  }
  : async () => { }

— https://github.com/gitbrent/PptxGenJS/blob/3c9ec1b687c174952166f6a34b5e87ebf69fa469/src/gen-media.ts#L23

However, a dyanamic import statement is known that it does not work as expected in the binary build packaged by pkg (@yao-pkg/pkg).

So I've updated the configuration of rollup output.dynamicImportInCjs to false, to apply downlevel transpiling for dynamic import() to use require().

This transpilation will break already ESM compatible import for the engine so I also have added the rollup plugin for keeping dynamic import() for the engine.