feat(cntr): resolve BE-36, BE-37, BE-38, BE-39 — rating, webhook logger, token blacklist, opening hours

[Tyler7x]

Summary

Implements four self-contained utility/service files in backend/cntr/, each with a paired unit test spec. All logic is pure TypeScript with no framework dependencies or external I/O.

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BE-38 — In-Memory JWT Token Blacklist (#977)

File: backend/cntr/token-blacklist.util.ts

• TokenBlacklist class backed by Map<string, Date>
• blacklist(jti, expiresAt) — stores the token
• isBlacklisted(jti) — returns false for unknown or expired JTIs
• purgeExpired(now?) — removes all entries whose expiresAt < now; accepts optional now param for deterministic tests

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BE-39 — Workspace Opening Hours Validator (#978)

File: backend/cntr/opening-hours.validator.ts

• Exports OpeningHoursEntry, ValidationResult interfaces and validateOpeningHours(hours)
• Validates HH:MM format with /^([01]\d|2[0-3]):[0-5]\d$/
• Rejects closeTime <= openTime when isClosed = false
• Rejects duplicate dayOfWeek entries
• Accumulates all errors before returning — no fail-fast

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BE-37 — Webhook Event Logger with Payload Sanitization (#976)

File: backend/cntr/webhook-event-logger.ts

• Exports WebhookEventLog interface and createWebhookEventLog(event, payload, status, error?)
• id generated via crypto.randomUUID()
• receivedAt is ISO 8601 string
• Sanitizes payload by removing keys matching /(card|cvv|pan|account_number)/i (case-insensitive)
• Original payload object is not mutated — operates on a shallow copy

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BE-36 — Workspace Rating Service (#975)

File: backend/cntr/workspace-rating.service.ts

• Exports WorkspaceRating interface, validateRating, and computeAverageRating
• validateRating throws RangeError for score outside 1–5 and Error for comment > 500 chars
• computeAverageRating([]) returns 0
• Average rounded to 1 decimal place via Math.round(avg * 10) / 10

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Test plan

• backend/cntr/token-blacklist.util.spec.ts — 6 tests covering unknown JTIs, valid tokens, expired tokens, purgeExpired with and without now
• backend/cntr/opening-hours.validator.spec.ts — 9 tests covering format errors, close≤open, duplicate days, multi-error accumulation, isClosed bypass, full week
• backend/cntr/webhook-event-logger.spec.ts — 7 tests covering UUID format, ISO date, sensitive key removal (all variants), no mutation, empty payload
• backend/cntr/workspace-rating.service.spec.ts — 13 tests covering all invalid scores, comment length boundary, all valid scores 1–5, average edge cases

Closes #975
Closes #976
Closes #977
Closes #978

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[yusuftomilola]

Perfect implementation