feat: establish catalog identity and atomic file ownership

docs/superpowers/specs/2026-10-12-catalog-core-design.md

@@ -1,6 +1,6 @@
 # Catalog core foundation — proposed design
 
-Status: draft for user approval; no product implementation authorized by this document.
+Status: domain rules and implementation plan approved by the user; bounded catalog-core implementation completed and independently reviewed. Broader #28 and M2/M3 acceptance remain open.
 
 ## Intent
 
@@ -23,7 +23,7 @@ No browse UI, moves, physical deletion, downloads, duplicate decisions, retry en
 or import crash-recovery fix in this first slice. Do not silently relabel unresolved
 M2/M3 acceptance as complete. No new framework or runtime dependency.
 
-## Proposed domain rules (require approval)
+## Approved domain rules
 
 1. A physical managed file has one durable catalog identity and belongs to at most
    one logical model. Unassigned files retain their file record. Shared ownership is
@@ -104,5 +104,7 @@ and serialized folder/model moves (#31/#32) follow as separately designed slices
 
 ## Approval boundary
 
-The ownership/unassigned-file/empty-model rules above are proposals, not existing
-user decisions. Approve or revise them before creating the implementation plan.
+The user approved these rules as the basis for the implementation plan, including
+single ownership, persistent unassigned files, empty models, independent same-title
+models and a required organizational home folder. The bounded plan was approved,
+implemented and independently reviewed; this does not mark #28 or M2/M3 complete.