fix(ui): keep permission dock buttons in view on long requests

Long permission.patterns push the dock footer buttons off-screen.
Cap the dock with a viewport-relative max-height that also reserves
the inherited sticky-header offset, and constrain the patterns grid
row with min-height: 0 / minmax(0, 1fr) so overflow-y: auto engages
instead of growing the wrapper. A bottom-only mask fades the scroll
edge; no JavaScript measurement or runtime resize observers needed.

Author: Arcadi4

packages/ui/src/components/message-part.css

@@ -720,7 +720,7 @@
   flex-direction: column;
   gap: 0;
   min-height: 0;
-  max-height: 100dvh;
+  max-height: min(40dvh, calc(100dvh - var(--sticky-accordion-top, 0px)));
 
   [data-slot="permission-body"] {
     display: flex;
@@ -746,6 +746,13 @@
     align-items: center;
   }
 
+  [data-slot="permission-row"]:has(> [data-slot="permission-patterns"]) {
+    flex: 1;
+    min-height: 0;
+    grid-template-rows: minmax(0, 1fr);
+    align-items: stretch;
+  }
+
   [data-slot="permission-icon"] {
     display: inline-flex;
     align-items: center;
@@ -792,8 +799,11 @@
     flex: 1;
     min-height: 0;
     overflow-y: auto;
+    overscroll-behavior: contain;
     scrollbar-width: none;
     -ms-overflow-style: none;
+    -webkit-mask-image: linear-gradient(to bottom, #000 calc(100% - 24px), transparent 100%);
+    mask-image: linear-gradient(to bottom, #000 calc(100% - 24px), transparent 100%);
 
     &::-webkit-scrollbar {
       display: none;