fix(ui): rerender pasted block rows

[AkhilTrivediX]

Summary

• Clear stale lastRenderedPath metadata when serializing copied form fields and nested rows.
• Ensure same-path block-row pastes trigger component rendering instead of leaving the block body blank.

Root cause

Clipboard data preserved render-location metadata while intentionally omitting non-serializable custom components. When a copied block row was pasted back to the same path, the stale render path matched the target path and skipped the server render required to restore those components.

Fixes #17375.

Validation

• pnpm exec vitest run --project unit packages/ui/src/elements/ClipboardAction/mergeFormStateFromClipboard.spec.ts --reporter=dot
• pnpm exec prettier --check packages/ui/src/elements/ClipboardAction/mergeFormStateFromClipboard.ts packages/ui/src/elements/ClipboardAction/mergeFormStateFromClipboard.spec.ts
• Regression test fails against the previous serializer and passes with this change.

[JarrodMFlesch]

Can you add a e2e test that shows the failure before this change was made?

[AkhilTrivediX]

Added an end-to-end regression assertion in test/fields/collections/Blocks/e2e.spec.ts.

The existing same-row copy/paste scenario now verifies that the block's rich-text editor is visible both before and after pasting the copied row back onto itself. This covers the blank block-body behavior caused by retaining lastRenderedPath for the same target path.

The update is in aecb30d. The PR checks triggered by the new commit are passing.