ojs-backend-postgres v0.2.0

• docs: add configuration reference to README
• refactor: extract storage interface methods
• fix: handle connection timeout gracefully
• feat: add health check endpoint
• build: update go.mod dependency to latest core version
• feat: implement graceful shutdown with drain timeout
• fix: correct retry backoff calculation for edge cases
• perf: optimize batch dequeue query performance
• fix: resolve race condition in concurrent job completion
• refactor: extract common middleware chain
• feat: add metrics endpoint for monitoring
• fix: correct SKIP LOCKED query for high concurrency
• feat: add connection pool metrics

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What's Changed

See the full release notes: https://github.com/openjobspec/openjobspec/blob/main/RELEASE_NOTES_v0.2.0.md