fix: enable scrolling in create cookbook modal

Added overflow-y: auto and max-height: 90vh to the modal to allow
scrolling when the form content exceeds viewport height. This fixes
the issue where the save button was inaccessible when creating
cookbooks with many filter options.

Changes:
- Modal now scrolls independently when content is too tall
- Modal limited to 90% viewport height
- Modal overlay allows scrolling with vertical padding
- Background page no longer scrolls when modal is open

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/web/src/styles/Cookbooks.css

@@ -247,6 +247,8 @@
   align-items: center;
   justify-content: center;
   z-index: 1000;
+  overflow-y: auto;
+  padding: 2rem 0;
 }
 
 .modal {
@@ -255,7 +257,10 @@
   padding: 2rem;
   max-width: 500px;
   width: 90%;
+  max-height: 90vh;
+  overflow-y: auto;
   box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
+  margin: auto;
 }
 
 .modal h2 {