feat: make Gloss the presentation challenge

[aronchick]

What changed

• makes the deliberately complicated 20-slide presentation the primary Gloss product
• adds the simple native-object gloss check workflow while keeping measurement as the support layer
• publishes the complete exact prompt and all twenty slide cases
• connects Gloss to Acid1, Acid2, and Acid3
• rebuilds the static site and launch film around the deck and GitHub collaboration
• updates the retronym to Generative Layout & Object Structure Standard
• removes the old metric-first product framing from public and hosted-service surfaces

Local release proof

• grader: Ruff, formatting, mypy, 220 tests, 86.45% coverage, build, dependency audit
• service: Ruff, formatting, mypy, 115 tests, 85.04% coverage, dependency audit
• corpus: 280/280 positive controls and 280/280 mutations detected
• launch: media, claims, hashes, links, headers, and HTML validation pass
• containers: grader runtime plus API, worker, and quarantine images build locally
• naming: no AcidSlide or old OOXML-scoring retronym remains in tracked text or PPTX packages