Add atomic Revit initial import

AGENTS.md

@@ -275,10 +275,20 @@ Phase 14.2 migration `0003` provides one implicit Revit CSV source per project,
 immutable import batches with original bytes plus the classified cell matrix,
 normalized source-room mappings and external objects unique by
 `(sourceId, ifcGuid)`. Source values, planning values and overrides are separate.
-The current repository is read-only; no runtime import command writes these
-tables yet. Snapshot/restore and portable project transfer schema version 4
+The general external-model repository is read-only; runtime writes belong only
+to typed command adapters. Snapshot/restore and portable project transfer schema version 4
 capture the complete external state and remap every internal UUID and link while
 preserving IFCGUIDs, source values, original bytes and the classified matrix.
+Import batches additionally store the monotonic project CSV configuration
+version introduced by additive migration `0004`; it is distinct from the CSV
+configuration JSON schema version.
+Confirmed initial state is written only through
+`external-import.apply-initial`. The command rechecks configuration version,
+original-byte SHA-256, parsed matrix, complete IFCGUID/source values, explicit
+planning overrides and internal project links in the shared transaction. It
+never creates or links a CircuitDeviceRow. Its exact inverse removes the whole
+unchanged external state, and Redo restores the same UUIDs and bytes. No public
+apply endpoint or staging wizard invokes this command yet.
 The central revision boundary creates an automatic logical snapshot after each
 25 new revisions and retains only the newest 12 automatic snapshots per
 project. Named snapshots are never removed by this retention policy.