Image resize handles missing in header/footer edit mode

[jedrazb]

Reported during manual testing of PR #264 (which fixes save round-trip for header images, issue #251).

Repro

1. bun run dev, open http://localhost:5173/.
2. Load any DOCX with a header.
3. Double-click the header to enter edit mode.
4. Paste an image (Cmd+V).

Expected: Image has draggable resize handles (same as in body).

Actual: Image renders as plain <img>, no handles. Cannot resize while in header/footer edit mode.

Root cause

The body editor uses a React NodeView (EditableImage) that adds resize handles, but InlineHeaderFooterEditor.tsx:209 builds a fresh ExtensionManager via createStarterKit() that registers the plain ImageExtension.toDOM() without that NodeView.

Suggested fix

Either:

• Plumb the same EditableImage React NodeView into the InlineHeaderFooterEditor's extension setup, or
• Move the resize-handle NodeView registration into ImageExtension itself (single source of truth).

Estimated fix

Medium. Need to share the React NodeView across two ProseMirror instances cleanly.