fix(cli,gateway): surface title errors from /new <name>

The contributor's PR silently swallowed ValueError from
SessionDB.set_session_title() with bare except Exception: pass.
Users typing /new <title> with an already-in-use title got an
untitled session and no feedback.

Changes:
- cli.py: catch ValueError from both sanitize_title() and
  set_session_title(); print the error and mark the session
  untitled in the banner (never echo the rejected title back).
- gateway/run.py: append a warning note to the reset reply on
  title rejection; reflect the accepted title in the header.
- Add regression tests for the duplicate-title path in CLI and
  gateway.

Also map exx@example.com -> @exxmen in scripts/release.py.

gateway/run.py

@@ -6898,14 +6898,26 @@ class GatewayRunner:
 
         # Set session title if provided with /new <title>
         _title_arg = event.get_command_args().strip()
+        _title_note = ""
         if _title_arg and self._session_db and new_entry:
+            from hermes_state import SessionDB
             try:
-                from hermes_state import SessionDB
                 sanitized = SessionDB.sanitize_title(_title_arg)
-                if sanitized:
+            except ValueError as e:
+                sanitized = None
+                _title_note = f"\n⚠️ Title rejected: {e}"
+            if sanitized:
+                try:
                     self._session_db.set_session_title(new_entry.session_id, sanitized)
-            except Exception:
-                pass
+                    header = f"✨ New session started: {sanitized}"
+                except ValueError as e:
+                    _title_note = f"\n⚠️ {e} — session started untitled."
+                except Exception:
+                    pass
+            elif not _title_note:
+                # sanitize_title returned empty (whitespace-only / unprintable)
+                _title_note = "\n⚠️ Title is empty after cleanup — session started untitled."
+        header = header + _title_note
 
         # Fire plugin on_session_reset hook (new session guaranteed to exist)
         try: