user-level-export-axis.md

@objectstack/spec	minor
@objectstack/plugin-hono-server	minor

feat: user-level export permission axis (#3544, #3391 follow-up)

export is a user-gated operation, not just "anyone who can list". A permission set can now deny export on an object while keeping read — matching Salesforce "Export Reports" / Dynamics "Export to Excel" / NetSuite "Export Lists" / SAP S_GUI 61.

• spec ObjectPermissionSchema gains an optional allowExport bit. It is deliberately OPTIONAL with no default so it is a backward-compatible opt-out: unset → inherits read (today's "can-list ⇒ can-export"), false → export denied while read is kept, true → granted.
• plugin-hono-server annotateEffectiveApiOperations derives userExportAllowed = allowExport !== false from the resolved per-object permission and threads it into resolveEffectiveApiMethods — so export derives from list ∧ userExportAllowed. When the axis removes export from an otherwise-open object, the object is now annotated (the effective set minus export) so the client hides the Export button; an unrestricted object with export still allowed stays unannotated (client default-allow).

Wires the userExportAllowed slot reserved in #3391 P1 — zero contract change to the derivation table or the frontend (it already consumes the effective apiOperations). Backward-compatible: existing permission sets (no allowExport) keep today's behavior everywhere.