Fix PWA theme color to match darker blue color scheme in 2025.8 (home-assistant#150896)

Co-authored-by: Claude <[email protected]>

Author: balloob

homeassistant/components/frontend/__init__.py

@@ -50,7 +50,7 @@
 CONF_FRONTEND_REPO = "development_repo"
 CONF_JS_VERSION = "javascript_version"
 
-DEFAULT_THEME_COLOR = "#03A9F4"
+DEFAULT_THEME_COLOR = "#2980b9"
 
 
 DATA_PANELS: HassKey[dict[str, Panel]] = HassKey("frontend_panels")