Changelog: New Metrics API Endpoint Added

[ellipsis-dev]

A new larger feature has been merged into the main langfuse repository: a comprehensive public metrics API endpoint.

Feature Summary:

• Introduced a new GET /api/public/metrics endpoint to fetch metrics with flexible query parameters.
• Query parameters include: view, dimensions, metrics, filters, timeDimension, fromTimestamp, toTimestamp, and orderBy.
• Added schema validation for queries and structured response types.
• Comprehensive tests for valid/invalid queries, authentication, and error handling.
• Documentation updated in openapi.yml and Postman collection.

Files changed:

• API definition: fern/apis/server/definition/metrics.yml
• OpenAPI spec: web/public/generated/api/openapi.yml
• Postman collection: web/public/generated/postman/collection.json
• Endpoint implementation: web/src/pages/api/public/metrics/index.ts
• Query/response types: web/src/features/public-api/types/metrics.ts
• Tests: web/src/__tests__/async/metrics-api.servertest.ts

Impact:

• Enables users to programmatically fetch metrics with custom queries.
• Ensures robust validation and error handling for API consumers.
• Improves documentation and testing coverage for public API endpoints.

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