Linked Comfy tabs show "Media input missing" for staged images #3

LoadImage choices come from cached node definitions. After reloading a linked
Comfy tab, or after uploading files once the definitions were loaded, a
project-staged image can show "Media input missing" although the file exists and
its thumbnail loads. Refresh the loader's options when a graph opens or after an
import, without changing the selected source, rewriting metadata or downloading
every schema on each selection.

Implementation status (2026-11-07)

PR #35 refreshes targeted native loader choices and verifies nested staged selections with HEAD requests. It preserves authored values/metadata, handles reopened/restored tabs and skips late updates after selection changes. Fifteen loader checks and 28 real Comfy-link browser checks pass; the final branch gate passes. Review/merge remains open. Current branch head: 27714436a18ad43b5e97bcca0371dfeb864f7669.