fix: read dashboard spa assets as utf-8

Co-Authored-By: Paperclip <noreply@paperclip.ing>

hermes_cli/web_server.py

@@ -10656,7 +10656,7 @@ def mount_spa(application: FastAPI):
         ``__HERMES_AUTH_REQUIRED__`` flag lets the SPA pick the right
         auth scheme for /api/pty and /api/ws (ticket vs token).
         """
-        html = _index_path.read_text()
+        html = _index_path.read_text(encoding="utf-8")
         chat_js = "true" if _DASHBOARD_EMBEDDED_CHAT_ENABLED else "false"
         gated = bool(getattr(app.state, "auth_required", False))
         gated_js = "true" if gated else "false"
@@ -10706,7 +10706,7 @@ def mount_spa(application: FastAPI):
         ):
             return JSONResponse({"error": "not found"}, status_code=404)
         prefix = _normalise_prefix(request.headers.get("x-forwarded-prefix"))
-        css = css_path.read_text()
+        css = css_path.read_text(encoding="utf-8")
         if prefix:
             for asset_dir in ("/fonts/", "/fonts-terminal/", "/ds-assets/", "/assets/"):
                 css = css.replace(f"url({asset_dir}", f"url({prefix}{asset_dir}")