GET /api/instances/:id/files (list) + /file (read), PUT /file (write) —
tenant-guarded, routed through requestScoped to the per-instance
corrosion.{license}.{instance}.files.cmd using the new agent's {op,path}
protocol (jailed to the instance root, symlink-safe). files.view /
files.manage perms. Foundation for the per-game config editor and for
fixing the legacy VueFinder File Manager (which still speaks the retired
Go fm_* protocol on the wrong subject and is broken under per-license
auth — separate reconciliation).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>