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>

hh/src/main.rs

@@ -99,7 +99,9 @@ fn main() -> Result<()> {
                 match net::authenticate(&ip, port, &name, &password, no_tls, insecure) {
                     Ok(s) => break s,
                     Err(e) if interactive => {
-                        eprintln!("✖ {e:#}\n  that handle didn't work (taken or full?) — pick another.");
+                        eprintln!(
+                            "✖ {e:#}\n  that handle didn't work (taken or full?) — pick another."
+                        );
                         name = prompt_handle()?;
                     }
                     Err(e) => return Err(e),
@@ -168,7 +170,7 @@ fn main() -> Result<()> {
 fn prompt_handle() -> Result<String> {
     use std::io::Write;
     loop {
-        print!("⛧ choose your handle: ");
+        print!("✝ choose your handle: ");
         std::io::stdout().flush()?;
         let mut s = String::new();
         if std::io::stdin().read_line(&mut s)? == 0 {