Keep artifact deletion optimistic across navigation

[baggiiiie]

Summary

Keep artifact deletion optimistic across navigation (redirection back to artifact page after deleting an artifact), so deleted cards do not appear after redirection

before

deletion-before-fix.mp4

after

artifact-delete-after.mp4

Linked issue

no issue open yet, will open one if preferred

Verification

• bun run format:check
• bun run lint
• bun run typecheck
• bun run test
• e2e — Artifacts · renaming and deleting in the console is what the agent sees next — recording

Checklist

• Added a changeset (bun run changeset), or this change needs none.
• Added or updated tests for the new behaviour.
• No secrets, credentials, or private data in the diff.

[baggiiiie]

the ci failures are outside of this PR's diff, details:

• apps/host-cloudflare/src/worker.e2e.node.test.ts: exceeded its 5s timeout. The test passes locally in 1.26s.
• cloud/mcp-session-cap-eviction.test.ts: failed after 110s because opening session-4 returned no mcp-session-id header.