feat(ui): stacking role badges in roster + chat; drop default pentagram

- introduce a Role model + App::host()/roles_of(): the host is the first
  occupant of the roster (shown the moment they join, no sandbox required),
  and roles are additive — a host who summoned a sandbox and can drive reads
  ✝⚡◆. Badges read the same ACL the broker enforces, so they can never
  advertise a power the room won't honour
- render the stacked badge in the clergy panel and inline next to the author
  on every chat message; split VirtualBox commands into their own help cluster
- default styling: the startup handle prompt now prints ✝ (crypt sigil)
  instead of the inverted pentagram
- README: document VirtualBox VMs, snapshot save/load, AI streaming + recall,
  the badge system, and the expanded theme set
- gitignore out-of-tree experiments, the heavy demo-build kit, and logs

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

.gitignore

@@ -17,6 +17,17 @@ secured_console_chat.egg-info/
 # Editor / OS
 .idea/
 
+# Logs / runtime scratch
+*.log
+err.log
+
+# Out-of-tree experiments (not part of hack-house)
+/experiments/
+/headroom/
+
+# Heavy / superseded demo-build kit (real demos live in video-toolkit)
+/docs/demo/
+
 # Project scratch
 /i-try/
 test_rsa.py