feat: Add Supplemental Feeds feature with UI and backend support

- Implemented the main view for Supplemental Feeds, displaying clients with Merchant Account IDs and their associated feed files.
- Added styling for the feeds page and its components, including headers, empty states, and dropdown menus for syncing actions.
- Created backend logic to generate supplemental feeds for clients, including file handling and data sanitization.
- Integrated new routes and views for managing feeds, ensuring proper data retrieval and display.
- Updated navigation to include the new Supplemental Feeds section.
- Added necessary documentation for CRON job management related to feed generation.

.htaccess

@@ -8,13 +8,16 @@ RewriteRule ^(.*)$ https://%1/$1 [R=301,L]
 RewriteCond %{SERVER_PORT} !=443
 RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=permanent]
 
+# Pliki TSV z feeds/ - serwuj statycznie
+RewriteCond %{REQUEST_URI} ^/feeds/.+\.tsv$ [NC]
+RewriteRule ^ - [L]
+
 # Statyczne zasoby - pomijaj
 RewriteCond %{REQUEST_URI} ^/(libraries|layout|upload|temp)/ [NC]
 RewriteRule ^ - [L]
 
-# Istniejące pliki/katalogi - pomijaj
-RewriteCond %{REQUEST_FILENAME} -f [OR]
-RewriteCond %{REQUEST_FILENAME} -d
+# Istniejące pliki - pomijaj (katalogi NIE, zeby /feeds trafialo do index.php)
+RewriteCond %{REQUEST_FILENAME} -f
 RewriteRule ^ - [L]
 
 # Wszystko inne → index.php