Agentic UI: Create site from import

[bcotrim]

Related issues

• N/A

How AI was used in this PR

Codex helped inspect the existing import paths, implement the end-to-end increment, and add focused tests. I reviewed the changes and manually exercised the local-web workflow, including failure, rollback, retry, and light/dark states.

Proposed Changes

• Add an Import from a backup option to Add a site that opens the system file picker or accepts a dropped backup, including SQL, and pre-fills an editable site name.
• Extend the legacy desktop Add Site import flow to accept SQL backups, matching the existing import backend support.
• Make imports safely retryable by retaining the selected file, resolving or uploading it on every attempt, and using collision-safe temporary paths.
• Keep the Electron IPC and local-web import behavior aligned, roll back a newly created site after an import failure, and open the usable site after a successful import.
• Show accessible progress, prevent duplicate actions and navigation only while work is active, and provide phase-specific failure guidance with retry and replacement-file actions.

Testing Instructions

1. Open Add a site, choose or drop a supported backup, and confirm the setup form opens directly.
2. Confirm the suggested name is sensible and editable.
3. Import a malformed backup and confirm the new local site is removed, the selected backup remains available, and the failure state offers Retry import and Choose another backup.
4. Retry and confirm a fresh uploaded path is used.
5. Confirm Close, Back, and duplicate submission are blocked only while the import is active.
6. In the legacy desktop Add Site flow, choose Import from a backup and confirm a .sql file is accepted.

Pre-merge Checklist

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

[wpmobilebot]

📊 Performance Test Results

Comparing 741002a vs trunk

app-size

Metric	trunk	741002a	Diff	Change
App Size (Mac)	1361.99 MB	1361.93 MB	0.06 MB	⚪ 0.0%

site-editor

Metric	trunk	741002a	Diff	Change
load	1080 ms	1079 ms	1 ms	⚪ 0.0%

site-startup

Metric	trunk	741002a	Diff	Change
siteCreation	7000 ms	6982 ms	18 ms	⚪ 0.0%
siteStartup	2352 ms	2355 ms	+3 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

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

[sejas]

I tested the PR importing new sites and during the onboarding flow and everything worked fine. I also tested with broken imports and the error is visible to users.

Onboarding:

Importing Progress:

Error import:

[sejas]

My agent recommends splitting this code between useState and useEffect, but I couldn't reproduce any issue with the existing code.

const [ selectedFile ] = useState< File | null >( peekPendingBackup );
useEffect( () => {
	clearPendingBackup();
}, [] );