[toakinrele]

Closes #115

Adds network and aws_creds pytest markers so the fast unit tests can be run separately from tests that need network access or AWS/GCS credentials.

• Registered markers in pyproject.toml
• conftest.py auto-tags tests based on which fixtures they use (download_gpkg, clean_s3_test, etc.), and auto-skips aws_creds
  tests when no AWS credentials are detected
• Explicitly marked the handful of tests that hit the network directly without a fixture (test_hf2ds.py, some of test_trouterestarts.py)
• Added a Makefile with test-fast / test-network / test-all targets

Local fast loop: make test-fast - 7 tests in ~3s instead of the full ~30 min suite, no credentials required.

[toakinrele]

Closing in favor of a new PR opened directly from CIROH-UA/forcingprocessor (branch pushed to upstream to allow AWS/GCS credential checks to run).