Studio: Fix the scroll that is stuck on blueprints gallery page in agentic UI

[katinthehatsite]

Related issues

Fixes STU-1852

How AI was used in this PR

It was used to help and identify the issue.

Proposed Changes

This PR ensures that the blueprints gallery page is visible in the agentic UI and that the top is not cut off.

Testing Instructions

• Pull the changes from this branch
• Start Studio with npm start
• Enable the Agentic UI feature flag from Studio -> Feature flags from the topbar
• Click on the New site -> Start from a blueprint option option
• Confirm that the blueprints screen is not cut off on the top
• Confirm that there are no other regressions in the UI

Before the changes (where the top of the screen was not visible)

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[katinthehatsite]

One thing that I was unsure about is where the option to upload the blueprint should start on the top of the screen or at the middle of the screen (similar to Start a new site):

For now, I left it towards the top of the screen but we can adjust if needed.

[wpmobilebot]

📊 Performance Test Results

Comparing ecad8c5 vs trunk

app-size

Metric	trunk	ecad8c5	Diff	Change
App Size (Mac)	1419.22 MB	1419.22 MB	0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	ecad8c5	Diff	Change
load	1128 ms	1053 ms	75 ms	🟢 -6.6%

site-startup

Metric	trunk	ecad8c5	Diff	Change
siteCreation	6535 ms	6533 ms	2 ms	⚪ 0.0%
siteStartup	2390 ms	2392 ms	+2 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[wojtekn]

Works as expected.