feat: add registry export controls

[Fhatu12]

What this changes

Adds CSV and JSON export controls to the registry page for the current-state export introduced in #139.

The controls use native links to the existing export endpoint because it already returns Content-Disposition: attachment with deterministic filenames. Registry search/filter/sort state is intentionally not included in export URLs.

Closes #140.

Verification

• pnpm format:check
• pnpm lint — passes with the existing unrelated scripts/capture-fixture.mjs unused-URL warning
• pnpm typecheck
• focused registry/export tests — 60 passed
• pnpm test
• pnpm build
• pnpm build:dashboard
• git diff --check

Independent QA also validated the exact candidate against an ephemeral PostgreSQL 16 database with all migrations applied:

• CSV download: HTTP 200
  • Content-Type: text/csv; charset=utf-8
  • Content-Disposition: attachment; filename="stenion-registry-current.csv"
• JSON download: HTTP 200
  • Content-Type: application/json; charset=utf-8
  • Content-Disposition: attachment; filename="stenion-registry-current.json"
• omitted format defaults to JSON
• unsupported format returns HTTP 400
• filtered registry query parameters do not alter export output
• native CSV/JSON anchors remain independent of registry filter/search/sort state
• desktop and narrow/mobile registry layouts were visually checked
• anti-vacuity mutation proved the new export-link assertions fail when the format mapping is wrong

Checklist

• Base branch is dev, not main.
• pnpm build, pnpm lint, pnpm typecheck, and repository validation pass.
• On-chain method/field confirmation: N/A — no adapter or on-chain changes.
• *Safety factors: N/A — no scoring changes.
• No fabricated numbers — no scoring/data computation changes.
• methodology/ update: N/A — no methodology change.
• No new dependencies.

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Project	Deployment	Actions	Updated (UTC)
stenion	Ready	Preview	Aug 31, 2026 10:49pm

[dubemoyibe-star]

Nice work bro 🔥🔥
I'll do a minimal review 🕊️

[dubemoyibe-star]

Nice work
Merging!!!!!