UI: 3-tab layout (Admin overview / My dashboard / Training) + Settings page

Frontend:
- App shell with 3 tabs: Overview (admin), My Dashboard (all incl admin), Training + Settings icon
- New Settings.vue: edit profile (name/email) + change password (verify current)
- New MyBoard.vue: personal win/lose + weak areas + summary (all roles)
- New Training.vue: product/group list -> personas; admin manage + add product
- Dashboard.vue -> admin overview with date-range filter + per-trainee stats
- Added i18n keys (EN/TH) and tab/settings styling (ui-ux-pro-max design system)

Backend:
- /api/auth/change-password (verify current pw) + PUT /api/auth/profile
- Allow admin to train: board/weak-areas/chat/personas/sessions open to user+admin+super_admin
- /api/analytics now accepts ?from=&to= date filter + returns per_user summary

Verified: frontend builds; change-password (wrong/ok), profile, board all pass via test client; security tests pass

backend/app/api/chat_routes.py

@@ -45,7 +45,7 @@ def _get_ready_group(s, gid: str) -> dict:
 
 @chat_bp.post("/<gid>/personas/<pid>/chat/start")
 @require_auth
-@require_roles("user")
+@require_roles("user", "admin", "super_admin")
 def start_session(gid: str, pid: str):
     s = _stores()
     group = _get_ready_group(s, gid)
@@ -85,7 +85,7 @@ def start_session(gid: str, pid: str):
 
 @chat_bp.post("/<gid>/personas/<pid>/chat/send")
 @require_auth
-@require_roles("user")
+@require_roles("user", "admin", "super_admin")
 def send_message(gid: str, pid: str):
     s = _stores()
     actor = current_user()
@@ -125,7 +125,7 @@ def send_message(gid: str, pid: str):
 
 @chat_bp.post("/<gid>/personas/<pid>/chat/finish")
 @require_auth
-@require_roles("user")
+@require_roles("user", "admin", "super_admin")
 def finish_session(gid: str, pid: str):
     """End the chat and produce the debrief via the judge-LLM (reveals latent fields)."""
     s = _stores()
@@ -168,7 +168,7 @@ def finish_session(gid: str, pid: str):
 
 @chat_bp.get("/sessions")
 @require_auth
-@require_roles("user")
+@require_roles("user", "admin", "super_admin")
 def my_sessions():
     s = _stores()
     uid = current_user()["id"]
@@ -178,7 +178,7 @@ def my_sessions():
 
 @chat_bp.get("/sessions/<sid>")
 @require_auth
-@require_roles("user")
+@require_roles("user", "admin", "super_admin")
 def get_session(sid: str):
     s = _stores()
     session = s["sessions"].get_or_none(sid)