Apply bot review comments: fix coverage upload condition and docker permissions

[Copilot]

Addresses three bot review comments from PR #4 to improve CI workflow reliability and security.

Changes

• Coverage artifact upload: Changed condition from if: always() to if: success() || failure() to skip upload when workflow is cancelled/skipped, not just when tests fail
• Coverage path simplification: Reduced redundant path patterns from coverage + coverage/**/* to coverage/
• Docker cache permissions: Added job-level actions: write permission to docker job to support GitHub Actions cache (type=gha) operations

# Before
if: always()
path: |
  coverage
  coverage/**/*

# After  
if: success() || failure()
path: coverage/

# Docker job now has explicit cache permissions
docker:
  permissions:
    contents: read
    actions: write

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