Add CI badge to README; rename config key directories → paths

[Copilot]

Two housekeeping improvements: add a Tests workflow status badge to the README and rename the verbose directories config key to the more concise paths.

Changes

• README.md — Added GitHub Actions badge for the Tests workflow; updated config docs to reflect paths
• config.yaml — Renamed top-level key directories → paths
• ontrack.py — Updated main() to read paths from config; renamed internal variable and log messages accordingly
• tests/test_ontrack.py — Updated all inline YAML config fixtures and log message assertions to use paths

Config before/after

# Before
directories:
  - /path/to/your/data

# After
paths:
  - /path/to/your/data