fix(invitation): archive the ended NICO100 event

[nicoechaniz]

Outcome

Archives the historical August 2 NICO100 page without removing the reusable invitation/coupon architecture.

• Replaces the admission form with a bilingual ended state and exact historical date.
• Removes the ticket POST, campaign code field, submit control, countdown and expired-room path.
• Sends visitors to the stable /eventos/#virtuales schedule for upcoming weekend gatherings.
• Marks the historical URL noindex, follow and removes time-specific copy that still described the event as current.
• Keeps the participant follow-up bot available for people who attended.

Current base and verification

Rebased on 2026-08-05 onto landing main 443ce96, including the canonical Meta commerce cutover and visible registration consent from PRs #35–#38. The archive remains isolated to invitacion/index.html and its tests.

• npm test: 65/65 passed.
• npm run build: passed.
• Controlled-clock source checks cover before opening, opening, start and after the old event; the permanent archive cannot reopen.
• Headless Chrome review at 1440×1000 and 390×844 previously confirmed the existing responsive composition and consent overlay; this rebase introduced no invitation-page conflict.
• git diff --check: passed.

Boundaries and rollback

No checkout, coupon backend, legal contract, Pixel behavior, credentials or production data changed. Rollback is a single revert of c0cde07.

Merging main publishes GitHub Pages, so this PR remains intentionally unmerged pending explicit production-deploy approval.

Closes #20.