Add flock_tap test suite and .gitignore

Adds pytest coverage for flock_tap.py's parsing, classification, and
byte/FRP/cloud-IP accounting, plus a .gitignore for Python caches and
capture/scan output artifacts.

The packet-level tests double as regression guards for the recently fixed
detection bugs (FRP auth-payload firing on data segments not just SYN,
no bytes_up inflation, and known-Flock-IP correlation); they fail against
the pre-fix code and pass after it. scapy-dependent tests skip cleanly when
scapy is unavailable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,13 @@
+# Python
+__pycache__/
+*.py[cod]
+*.egg-info/
+.pytest_cache/
+.venv/
+venv/
+
+# Capture / scan outputs
+*.pcap
+report.json
+creds_*.txt
+s3_urls_*.txt