test: improve test coverage

[svietry]

Summary

• Improve unit test coverage from 62.9% → 67.6%, bringing 3 packages to 100% coverage (internal/logger, internal/tracker, pkg/connection)
• Add 510 lines of new tests across 7 files — 3 new test files and 4 extended existing test files
• All new tests are pure unit tests with no AWS credentials or external dependencies required

What changed

New test files:

• pkg/connection/connection_test.go — table-driven tests for AnchoreInfo.IsValid() (6 cases)
• internal/tracker/time_test.go — tests for TrackFunctionTime
• pkg/lib_test.go — test for SetLogger

Extended test files:

• pkg/inventory/report_test.go — TestHandleReport (dry run, valid/invalid anchore, quiet modes) and Test_reportToStdout (JSON output verification)
• pkg/inventory/ecs_test.go — Test_buildContainerTagMap (empty tasks, @ images, clean tags, mixed, nil digest)
• pkg/reporter/reporter_test.go — Test_prepareRequest (URL, auth, headers, body) and Test_fetchVersionedAPIPath (v1/v2/error responses)
• internal/logger/logger_test.go — TestNoOpLoggerMethods and TestZapLoggerMethods covering all wrapper methods (Debug, Debugf, Warn, Warnf, Error, Info)

Test plan

• go test ./... passes with no failures
• No changes to production code