Add unit tests to achieve ≥95% line coverage with Karma threshold enforcement

[devin-ai-integration]

Summary

Adds and improves Jasmine unit tests across the petclinic-angular project to reach ≥95% line coverage and ≥85% branch coverage, with Karma configured to enforce these thresholds and fail the build if they are not met.

Final coverage: Statements 98.3%, Branches 95.45%, Functions 96.41%, Lines 98.13% (177 tests, all passing)

Configuration changes:

• karma.conf.js: Added coverage-istanbul reporter, text-summary output, and global coverage thresholds (95% statements, 85% branches, 90% functions, 95% lines). Removed top-level browsers array (browsers are specified via CLI args or customLaunchers).
• angular.json: Added "codeCoverage": true to default test options so npm run test-headless generates coverage and enforces thresholds without needing --code-coverage flag.

Test changes:

• New spec files: error.service.spec.ts, vet-resolver.spec.ts, spec-resolver.spec.ts
• Rewritten service specs: pet.service, pettype.service, specialty.service, vet.service, visit.service — replaced minimal stubs with proper HttpTestingController-based tests covering all CRUD methods
• Expanded component specs (20+ files): Added tests for error handling paths (throwError), navigation methods, form submissions (success + error), delete flows, and ngOnInit loading across all owner/pet/pettype/specialty/visit/vet components

Review & Testing Checklist for Human

• browsers removal in karma.conf.js (line 6): The top-level browsers: ['Chrome', 'ChromeHeadless', 'ChromeHeadlessCI'] was removed. Verify that local ng test (without --browsers flag) still launches a browser correctly — Angular CLI should handle this, but confirm it doesn't break the local dev workflow.
• codeCoverage: true as default in angular.json: This means every ng test run generates coverage reports, which adds overhead. Confirm this is acceptable for local development speed, or consider moving it back to a CI-only configuration.
• Service spec rewrites: pet.service.spec.ts, visit.service.spec.ts, etc. were fully rewritten. Spot-check that no original test intent was lost (e.g., the original owner.service.spec.ts error-handling test at line 183 had a known bug with misplaced fail/error callbacks — verify the new tests adequately cover error paths).
• Run npm run test-headless locally and confirm all 177 tests pass and the coverage summary is printed with thresholds enforced.

Notes

• No production code was modified — only test files, karma.conf.js, and angular.json.
• Some component test stubs were extended with additional methods (e.g., deleteOwner, updateVisit) to support the new test cases. These match the real service method signatures.

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/cb173ce6c59a4c71858e0d5b3598b66e

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[devin-ai-integration]

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 4 additional findings.