chore: add state-hub offline inbox and FR for ingest support

- state-hub-inbox/: convention for queuing progress events during
  degraded-mode sessions (no tunnel to State Hub)
- First pending event: Railiance01 bootstrap milestone (T03-T05)
- contrib/feature-requests/: FR for automated inbox ingest in state-hub
- README documents the drain procedure until automation is in place

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

state-hub-inbox/2026-03-08-railiance01-bootstrap.yaml

@@ -0,0 +1,18 @@
+type: progress_event
+topic_id: ca369340-a64e-442e-98f1-a4fa7dc74a38
+workstream_id: bf40b47e-be5b-4930-a7d2-362e76b943bb
+event_type: milestone
+summary: "HostEurope server (Railiance01) bootstrapped and hardened"
+detail:
+  tasks_completed: [T03, T04, T05]
+  server: Railiance01
+  ip: 92.205.62.239
+  changes:
+    - Extended base role with fail2ban, UFW k3s/Flannel rules, HISTCONTROL
+    - Fixed dynamic inventory script JSON format
+    - Added roles_path to ansible.cfg
+    - Bootstrapped server: UFW active, fail2ban running, SSH hardened
+  smoke_tests_passed: true
+status: pending  # state-hub sets to "ingested" after processing
+recorded_at: "2026-03-08"
+source_repo: railiance-hosts