release: add owner-confirmed v4 context preview

[fomin-dima]

Outcome

Adds preview data release 4.0.0-rc.1+20260812 from the owner-confirmed 20-row matrix of latest publicly documented component-line contexts.

Scientific boundary

• Reuses the selected v3 state-event evidence and source links.
• Does not claim current implementation or software/data availability.
• Does not claim implementation quality, scientific validity, or field suitability.
• Keeps the portal beta / not accepted; this PR does not activate stable v4.

Verification

• npm run check: pass (822.4 s; 151 tests plus release, scale, accessibility, and browser fixtures).
• Full v4 release validator: 20 contexts, 1222 works, 117 evidence summaries, 126 graphs.
• Double build: 578 release files byte-identical.
• Resolver: 20/20 last_known / resolved; 0 unknown.
• Production home gate: PREVIEW, schema 4.0.0, exact counts.
• Route budgets: 36721 HTML routes; link check: 1338229 local references.

The immutable v3 release remains unchanged. Owner D-48/D-49 review and stable A/B publication remain later gated steps.