Add stable cursor pagination for /api/exports

[Eldren-cmd]

Closes #907

Summary

• Adds opaque cursor pagination for GET /api/exports using stable (created_at, id) ordering via exportedAt DESC, id DESC
• Returns pagination.hasMore and pagination.nextCursor while preserving legacy offset pagination when no cursor is supplied
• Validates query params at the route boundary and returns structured 400 validation errors for invalid cursors/limits
• Prevents non-admin callers from listing another developer’s exports via developerId
• Documents the visible pagination behavior in docs/exports-access-logs.md
• Fixes the existing error handler envelope call so validation errors serialize correctly

Testing

• node_modules\.bin\jest.cmd src/routes/exports.test.ts src/services/reportExporter.test.ts --runInBand --forceExit --coverage --collectCoverageFrom=src/routes/exports.ts --collectCoverageFrom=src/services/reportExporter.ts
  • 19 tests passed
  • Changed-file coverage: exports.ts 97.87% lines, reportExporter.ts 96.38% lines
• node_modules\.bin\eslint.cmd src/routes/exports.ts src/services/reportExporter.ts src/routes/exports.test.ts src/middleware/errorHandler.ts
• Filtered tsc --noEmit showed no errors for touched files

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[greatest0fallt1me]

All checks green — merging. Nice job! 🚀

[Eldren-cmd]

Thank you veery much for all the comments. Your reolving and communication skills are excellent, glad to have worked with you. Thanks