fix: ashburn relay playbooks and document DZ tunnel ACL root cause

Playbook fixes from testing:
- ashburn-relay-biscayne: insert DNAT rules at position 1 before
  Docker's ADDRTYPE LOCAL rule (was being swallowed at position 3+)
- ashburn-relay-mia-sw01: add inbound route for 137.239.194.65 via
  egress-vrf vrf1 (nexthop only, no interface — EOS silently drops
  cross-VRF routes that specify a tunnel interface)
- ashburn-relay-was-sw01: replace PBR with static route, remove
  Loopback101

Bug doc (bug-ashburn-tunnel-port-filtering.md): root cause is the
DoubleZero agent on mia-sw01 overwrites SEC-USER-500-IN ACL, dropping
outbound gossip with src 137.239.194.65. The DZ agent controls
Tunnel500's lifecycle. Fix requires a separate GRE tunnel using
mia-sw01's free LAN IP (209.42.167.137) to bypass DZ infrastructure.

Also adds all repo docs, scripts, inventory, and remaining playbooks.

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

.gitignore

@@ -0,0 +1,3 @@
+.venv/
+sessions.duckdb
+sessions.duckdb.wal