feat: improved account handling for db transient errors - closes #85

[petruki]

This pull request introduces several improvements to error handling and retry logic in the account handler and repository layers, along with corresponding tests to ensure robustness against transient failures and clearer error semantics. The changes also include minor dependency updates.

Error handling and retry logic improvements:

• Refactored CoreHandler.StartAccountHandler to extract and centralize error handling for account fetching, repository data fetching, and snapshot version fetching into dedicated methods (fetchActiveAccount, fetchRepositoryData, fetchSnapshotVersion). These methods now implement retry logic for transient errors and handle empty payloads and not-found cases more explicitly. ([src/core/handler.goL72-L127](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-62d3ec899cd35ae67b481dc138423870051a4a408db73cf81bc39c93fc2645c6L72-L127))
• Added new test cases and fake implementations in handler_test.go to verify retry behavior when fetching accounts or snapshot versions fails temporarily or returns empty payloads. ([[1]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-f3c9dab995e264eb5cfe9cfcae26d3e29d9c9cd4ddb115da4a2658a3aa96de47R350-R380), [[2]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-f3c9dab995e264eb5cfe9cfcae26d3e29d9c9cd4ddb115da4a2658a3aa96de47R482-R513), [[3]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-f3c9dab995e264eb5cfe9cfcae26d3e29d9c9cd4ddb115da4a2658a3aa96de47R539-R571), [[4]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-f3c9dab995e264eb5cfe9cfcae26d3e29d9c9cd4ddb115da4a2658a3aa96de47R728-R772))

Repository error normalization:

• Introduced ErrAccountNotFound as a standardized error for missing accounts, and added the normalizeAccountError helper to map MongoDB's ErrNoDocuments to this error. Updated repository methods and tests to use and assert this error consistently. ([[1]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-3426a5fabfd9da26b8141f7a74935c2fdfaa1f555e4d79eaa22ce3c77c2c56beR14-R15), [[2]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-3426a5fabfd9da26b8141f7a74935c2fdfaa1f555e4d79eaa22ce3c77c2c56beL63-R65), [[3]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-3426a5fabfd9da26b8141f7a74935c2fdfaa1f555e4d79eaa22ce3c77c2c56beR108-R116), [[4]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-3426a5fabfd9da26b8141f7a74935c2fdfaa1f555e4d79eaa22ce3c77c2c56beL138-R157), [[5]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-2f8770a6003aede5d1db854ce77ab6b8bdd085d844361af1146f828f1630ee34R84), [[6]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-2f8770a6003aede5d1db854ce77ab6b8bdd085d844361af1146f828f1630ee34R107), [[7]](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-2f8770a6003aede5d1db854ce77ab6b8bdd085d844361af1146f828f1630ee34R252-R286))

Dependency and workflow updates:

• Updated the github-script GitHub Action from v7 to v9 for PR details retrieval in the Sonar workflow. ([.github/workflows/sonar.ymlL19-R19](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-9a1c250ec072fc76ad44435cd9462d5693ea81f304d650922d3c2792bef267c2L19-R19))
• Upgraded the github.com/cloudflare/circl Go module from v1.6.3 to v1.6.4. ([go.modL19-R19](https://github.com/switcherapi/switcher-gitops/pull/95/files#diff-33ef32bf6c23acb95f5902d7097b7a1d5128ca061167ec0716715b0b9eeaa5f6L19-R19))

These changes collectively enhance the reliability and maintainability of the codebase by making error handling more robust and explicit.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud