refactor(frontend): remove disconnected waitlist client surfaces

[SHAURYAKSHARMA24]

Summary

Remove unused waitlist modal, hook and private API adapter with their obsolete tests. Current self-hosted landing routes remain covered. Preserve public waitlist endpoint, generated contract, historical migrations and records.

Linked issue

Related to #544.

Scope

Audit F18; baseline dev df0e82be3d7b2b7d846eefc1bcf82bde834936f2. This corrects independently verified existing behavior and advances the linked issue without adding product scope.

What changed

Remove unused waitlist modal, hook and private API adapter with their obsolete tests. Current self-hosted landing routes remain covered. Preserve public waitlist endpoint, generated contract, historical migrations and records.

Acceptance criteria completed

Implementation and targeted regression coverage below. See remaining work for conditions not verified.

Testing performed

7 product-surface regressions passed; clean frontend install, ESLint and production build passed. Import search confirms only removed tests and adapter referenced the modal/hook.

Current head: 6ebb683e9d337fa683605f2125068a4e1ab4dda9; check snapshot appears below.

Screenshots

Local screenshots and browser measurements are recorded in the remediation delivery report where applicable. Backend-only changes use contract/regression evidence.

Security and data considerations

Preserves owner scoping, source provenance, sealed graph contracts and historical data. No security gate weakened. Rollback: revert this scoped commit; see issue for migration/deployment implications.

Dependencies and blocked work

Independent dev-based PR unless explicitly stated in the issue. No unmerged changes included.

Scope changes or remaining work

Partial cleanup only: public API deprecation or retirement remains an explicit Parth decision in #544. No OAuth changes or historical data deletion.

Please review @parthrohit22.

Contributor checklist

• Targets dev; dedicated fork branch from latest dev; issue claimed.

• Scope/evidence recorded; unrelated changes and secrets excluded.

• Targeted validation results reported accurately.

• Required current-head CI and maintainer review complete.

Current-head remediation validation

Head: 6ebb683e9d337fa683605f2125068a4e1ab4dda9.

7 product-surface regressions passed; clean frontend install, ESLint and production build passed. Import search confirms only removed tests and adapter referenced the modal/hook.

Partial cleanup only: public API deprecation or retirement remains an explicit Parth decision in #544. No OAuth changes or historical data deletion.

Checks at delivery: Repository Hygiene: SUCCESS; Analyze (javascript-typescript): SUCCESS; Analyze (python): SUCCESS; API Contract Drift: SUCCESS; Frontend: FAILURE; Backend: SUCCESS; Docker Build: SUCCESS; Marketing Site: SUCCESS; Prototype Browser Acceptance: SKIPPED; Vercel: FAILURE; CodeQL: SUCCESS. Required checks/reviews must pass before merge; deployment authorization was not granted.

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