Re-running describe output loses page translations, nanoflow annotations/export level, Java action export level, snippet Type

[ako]

Plan item 0.4 in PROPOSAL_mdl_beta_syntax_freeze.md §8.1. Verified by comparing raw BSON on PedApp before and after running each document's describe output unchanged.

Losses

1. Page texts (FeedbackModule.ShareFeedback, Administration.Account_Overview):
   • A text whose en_US value is empty is dropped together with all its translations (113 → 102 overall).
   • A caption with en_US '' and nl_NL 'Knop' becomes en_US 'Knop', because describe falls back to another language.
2. Nanoflow ACT_Feedback_UploadImage:
   • The annotation connectors are dropped (3 → 0), so the annotations disappear from the next describe.
   • ExportLevel 'Hidden', UseListParameterByReference and ReturnVariableName are lost (mdl/executor/cmd_nanoflows_create.go).
3. Java action XSS_Sanitizer:
   • ExportLevel becomes Public; it is hardcoded at mdl/executor/cmd_javaactions.go:369.
   • ActionDefaultReturnName is lost. describe emits both only as comments.
4. Snippet _ReadMe: Type 'Web' becomes ''.
5. Plain create: describe emits create rather than create or modify for association, Java action and module role, so its output fails on an existing document.

Fix

Carry each value, or refuse the rebuild. Refusing is better than a silent drop. Each fixed case is removed from the round-trip harness allowlist (#703). Split into separate PRs per document type if they grow. Follow /mxcli-dev:fix-issue.