Agentic UI: separate the agentic features toggle from the classic UI switcher

[bcotrim]

Related issues

• Fixes STU-2097

How AI was used in this PR

Implemented with Claude Code, reviewed and verified manually.

Proposed Changes

The Agentic features toggle in Settings → AI now disable AI feature from the Agentic UI
Reintroduces the "switch to classic UI" toggle in Settings.

Settings	AI Settings

Testing Instructions

1. Enable the new Studio Agentic UI and open Settings.
2. In the Settings tab, confirm a Studio experience section with a Switch to classic button. Click it — the window reloads into the classic UI. Switch back to the new UI,.
3. Open the AI tab and switch Agentic features off. You should stay in the new UI (no reload into classic).
4. Click a site in the sidebar: it opens the Overview screen, not a chat. Restart the app — it opens on the overview and the toggle is still off.
5. Open the site dropdown and confirm previews, sync and publishing are still available.
6. Switch Agentic features back on and confirm chat returns.
7. Sign out (or go offline) with the toggle on and confirm the existing sign-in / offline behaviour is unchanged.
8. Check both light and dark mode.

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 0e71fb9 vs trunk

app-size

Metric	trunk	0e71fb9	Diff	Change
App Size (Mac)	1362.08 MB	1362.04 MB	0.04 MB	⚪ 0.0%

site-editor

Metric	trunk	0e71fb9	Diff	Change
load	1078 ms	1084 ms	+6 ms	⚪ 0.0%

site-startup

Metric	trunk	0e71fb9	Diff	Change
siteCreation	7021 ms	7045 ms	+24 ms	⚪ 0.0%
siteStartup	2348 ms	2398 ms	+50 ms	🔴 2.1%

---

Results are median values from multiple test runs.

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

[shaunandrews]

Can we get rid of the extra whitespace at the top of these cards? There should be equal spacing all the way around the card.

[nightnei]

LGTM and confirm that works as expected 👍