fix(ui): inject window.FRONTEND_TYPE from server + rename SHOP→STOREFRONT

Server now injects window.FRONTEND_TYPE in all base templates via
get_context_for_frontend(). Both log-config.js and dev-toolbar.js read
this instead of guessing from URL paths, fixing:
- UNKNOWN prefix on merchant pages
- Incorrect detection on custom domains/subdomains in prod

Also adds frontend_type to login page contexts (admin, merchant, store).

Renames all [SHOP] logger prefixes to [STOREFRONT] across 7 files
(storefront-layout.js + 6 storefront templates).

Adds 'merchant' and 'storefront' to log-config.js frontend detection,
log levels, and logger selection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/core/static/storefront/js/storefront-layout.js

@@ -5,11 +5,11 @@
  * Works with store-specific themes
  */
 
-const shopLog = {
-    info: (...args) => console.info('🛒 [SHOP]', ...args),
-    warn: (...args) => console.warn('⚠️ [SHOP]', ...args),
-    error: (...args) => console.error('❌ [SHOP]', ...args),
-    debug: (...args) => console.log('🔍 [SHOP]', ...args)
+const shopLog = window.LogConfig?.createLogger('STOREFRONT') || {
+    info: (...args) => console.info('🛒 [STOREFRONT]', ...args),
+    warn: (...args) => console.warn('⚠️ [STOREFRONT]', ...args),
+    error: (...args) => console.error('❌ [STOREFRONT]', ...args),
+    debug: (...args) => console.log('🔍 [STOREFRONT]', ...args)
 };
 
 /**