stardust:diff — prototype ↔ build reconcile

Two probes that compare a source prototype against a built page. They catch disjoint failure classes — run BOTH; either alone gives a false "looks fine".

Both are framework-agnostic Playwright probes that compare two rendered URLs by computed style + DOM (not pixels). All stack-specific language lives in a profile (--profile eds|generic); the comparison logic is generic.

When to use

• After converting a prototype to EDS (the stardust:deploy skill's Step 10) — use --profile eds.
• Any "does the build match the design?" check between two rendered URLs (a Figma export vs a React build, a legacy page vs a rebuild) — use --profile generic.
• Inside a conversion/QA workflow as the validation gate (see Workflow use).

Not for: a single static file with no JS decoration (use the build/harness URL so components are decorated — a raw .plain.html has no roles to classify).

The two probes