UN-3185: Pin LLM profile form submit button as a sticky footer (#2119)

* UN-3185: Pin LLM profile form submit button as a sticky footer

In the prompt-studio Settings modal, the LLM-profile Add/Edit form put its
submit button (Update/Add) as the last element in normal flow inside a fixed
800px scroll column. When the form is tall — e.g. Advanced Settings expanded —
the button flowed past the modal's visible area and appeared to overflow.

- Make the button a sticky footer (position: sticky; bottom: 0) with a solid
  themed background so it stays pinned at the bottom of the scroll column and
  fields scroll beneath it.
- The form root's .settings-body-pad-top declared overflow-y: auto with no
  bounded height — a dead nested scroll context that would stop the sticky
  footer from pinning to the real scroller (.conn-modal-col). Override it back
  to visible for this form (scoped via .add-llm-profile-scroll-root).

Verified the sticky pinning against the real CSS rules; build green, biome clean.

* Apply suggestion from @greptile-apps[bot]

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
Signed-off-by: Jaseem Jas <89440144+jaseemjaskp@users.noreply.github.com>

---------

Signed-off-by: Jaseem Jas <89440144+jaseemjaskp@users.noreply.github.com>
Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: jaseemjaskp

frontend/src/components/custom-tools/add-llm-profile/AddLlmProfile.css

@@ -1,5 +1,27 @@
 /* Styles for AddLlmProfile */
 
+/* The settings modal's content column (.conn-modal-col) is the real scroll
+   container. .settings-body-pad-top declares its own overflow-y: auto with no
+   bounded height, which does nothing except register a nested scroll context
+   that would stop the sticky footer below from pinning to .conn-modal-col.
+   Drop it back to visible for this form. */
+.settings-body-pad-top.add-llm-profile-scroll-root {
+  overflow: visible;
+}
+
+/* Pin the submit button to the bottom of the scrollable panel so it stays
+   visible as the form grows (e.g. Advanced Settings expanded) instead of
+   flowing past the modal. Background is set inline from the antd theme token
+   so scrolling fields don't show through. */
+.add-llm-profile-footer {
+  position: sticky;
+  bottom: 0;
+  z-index: 1;
+  margin-bottom: 0;
+  padding-top: 12px;
+  border-top: 1px solid var(--ant-color-border-secondary, #f0f0f0);
+}
+
 .add-llm-profile-row {
   width: 100%;
 }

frontend/src/components/custom-tools/add-llm-profile/AddLlmProfile.jsx

@@ -453,7 +453,7 @@ function AddLlmProfile({
   };
 
   return (
-    <div className="settings-body-pad-top">
+    <div className="settings-body-pad-top add-llm-profile-scroll-root">
       <Form
         form={form}
         layout="vertical"
@@ -633,7 +633,10 @@ function AddLlmProfile({
             />
           </div>
         </SpaceWrapper>
-        <Form.Item className="display-flex-right">
+        <Form.Item
+          className="display-flex-right add-llm-profile-footer"
+          style={{ backgroundColor: token.colorBgContainer }}
+        >
           <Space>
             <CustomButton type="primary" htmlType="submit" loading={loading}>
               {editLlmProfileId ? "Update" : "Add"}