feat(ssh): add bootstrap-ssh-ca role for OpenBao SSH user CA trust

Deploy TrustedUserCAKeys, auth_principals from ssh_principals.yaml, and
Makefile targets bootstrap-ssh-ca / bootstrap-ssh-ca-host (NET-WP-0020 T5).

ansible/inventory/ssh_principals.yaml

@@ -0,0 +1,19 @@
+# Central SSH certificate principals inventory — synced with ops-warden actor
+# principals (wiki/ActorInventoryPatterns.md). Public data only.
+
+ssh_principals:
+  CoulombCore:
+    users:
+      tegwick:
+        - agt-task-bridge
+        - agt-interhub-bootstrap
+        - adm-full
+        - atm-backup-daily
+
+  Railiance01:
+    users:
+      tegwick:
+        - agt-task-bridge
+        - agt-interhub-bootstrap
+        - adm-full
+        - atm-backup-daily