Improvement: Raise CI coverage threshold to 90% + enable branch coverage

[lavrovvalera]

What

After Tasks

• Improvement: Increase unit test coverage to 90% line + branch: score/time/ API #44
• Improvement: Increase unit test coverage to 90% line + branch: score/TimeDaemon/ #45
• Improvement: Increase unit test coverage to 90% line + branch: score/TimeSlave/ #46

are complete and all components reach 90% line +
90% branch coverage, enforce the new threshold in the CI pipeline.

Update .github/workflows/code_coverage.yml:

# Before:
min-coverage: 85

# After:
min-coverage: 90
genhtml-extra-flags: "--branch-coverage"

Why

Raising the threshold without first reaching it (Tasks 5a–5c) would break
all PRs. This task is the final enforcement step — it gates the CI against
regressions below 90%.

References

• Current coverage workflow:
  https://github.com/eclipse-score/inc_time/blob/main/.github/workflows/code_coverage.yml
• Reusable workflow parameters (min-coverage, genhtml-extra-flags):
  https://github.com/eclipse-score/cicd-workflows/blob/main/.github/workflows/cpp-coverage.yml

Estimates for realization

S - Day

Category

• Affects Detailed Design

Requirements / Architecture

• Requirements / Architecture are not affected by this change?