SCRIP-SITE-007: deliver a readable frozen full-work diagnostic report #267

Product outcome

Turn the existing source-free benchmarks/fantlab/work270306-wikisource-diagnostic.json into a readable offline HTML report using a standard-library CLI. This adopts the useful SCRIP-SITE-007 local work into GitHub; it is not a new corpus or parity exercise.

Scope / claim

Claimed by andy-zen-dev for scriptorium/frozen_diagnostic_report.py, its tests and user documentation, and proportional queue/changelog reconciliation. Base at selection: abe7bb889ef98437ba9faef5a79b023499556991 after #266 merged. No other PR is currently open.

Acceptance

• Render the existing 28 rows (23 numeric actuals; 5 missing) as expected / actual / raw delta, grouped by metric family, with explicit units and readable missing states.
• Preserve replay/source hashes and historical diagnostic-only/unknown-source evidence. Do not infer parity, invent similarity scores, or change analyzer formulas.
• Fail closed on schema/field drift, non-finite values, invalid delta arithmetic, false source-text flags, and pass/fail promotion.
• Deterministic offline HTML, escaped text, responsive tables, keyboard access, and create-only CLI output.
• Run focused regressions and validate/render the actual current repository diagnostic; require exact-head hosted full-suite evidence before later acceptance/merge.

Publication boundary

This PR delivers the standalone report, not live Pages activation. SCRIP-SITE-008 Pages integration and reader-first home remain subsequent product tasks. The old local integration package must be corrected and tested against the real renderer before adoption; its self-test alone is not integration evidence.

M1/M2 remain open. No source text is acquired or published.