Add settings page tabs and show env API keys with last four digits.

System settings now use the same CSS tab layout as env config; sensitive env fields display masked values from .env while keeping save-on-empty behavior.

Co-authored-by: Cursor <cursoragent@cursor.com>

crypto_monitor_gate/app.py

@@ -7053,6 +7053,7 @@ def render_main_page(page="trade", embed_mode=None):
     from lib.instance.instance_settings_lib import settings_page_context
     from lib.instance.instance_display_prefs_lib import display_prefs_template_context
 
+    _display_ctx = display_prefs_template_context(get_db)
     template_ctx = dict(
         page=page,
         key=key_list,
@@ -7143,9 +7144,10 @@ def render_main_page(page="trade", embed_mode=None):
             has_active_positions=bool(order_list),
         ),
         **embed_context_extras("gate"),
-        **display_prefs_template_context(get_db),
+        **_display_ctx,
         **settings_page_context(
             page,
+            display=_display_ctx["display"],
             instance_base_dir=BASE_DIR,
             exchange_key="gate",
             exchange_display=EXCHANGE_DISPLAY_NAME,