export-as-pptx-screenshots

# Export as PPTX (screenshots) Export an HTML slide deck to a `.pptx` as full-bleed PNG images. Pixel-perfect, not editable. One `gen_pptx` tool call. ### Steps 1. `show_to_user` the deck. 2. Call `gen_pptx`: ```jsonc { "mode": "screenshots", "width": 1920, "height": 1080, "slides": [ { "showJs": "goToSlide(0)", "selector": "body" }, // selector unused in screenshot mode but required { "showJs": "goToSlide(1)", "selector": "body" } ], "hideSelectors": [".nav", ".progress"], // If the deck wraps slides in a transform:scale() container, name it here so // the deck is forced to width × height inside the locked iframe. "resetTransformSelector": ".slide-container", "filename": "my-deck" } ``` If — and only if — the user asked for Google Slides, also pass `"offer_google_slides": true`: the export dialog gains a 'Send to Google Slides' button, and the upload happens only if they click it. `slides[].delay` defaults to 600ms — bump if transitions are slower. #### If the deck uses the `<deck-stage>` starter component - `resetTransformSelector: "deck-stage"` — same as editable mode; the component drops its shadow-DOM `transform: scale()` so the slides fill the locked iframe. - `slides[N].showJs`: `"document.querySelector('deck-stage').goTo(N)"` — 0-indexed, so slide 1 is `goTo(0)`. - `hideSelectors` is unnecessary — the overlay and tap-zones live in shadow DOM and aren't captured. ### Validation Same flags as editable mode. Watch for `duplicate_adjac...