Adopt Commonlib storage path contracts

Use the shared Node adapter and retain one comparison policy throughout
each CLI scan. Propagate permission and I/O failures instead of reporting
absence or a successful partial scan.

Use shared namespace and comparison helpers in Obsidian while preserving
its Vault APIs and alias policy. Cover native spelling and host filename
compatibility, and document the dependency and integration boundaries.

docs/design_docs/unicode_path_identity.md

@@ -27,6 +27,16 @@ Obsidian hosts, moves the setting to General Settings, and defaults new
 synchronisation environments to NFC. The original dates
 and reviewed versions above remain the historical baseline.
 
+## Unreleased shared storage boundary
+
+The CLI adopts Commonlib's shared Unicode resolver and typed physical-I/O
+ports. Each NFC scan retains one comparison-policy snapshot; directory and
+permission errors propagate instead of producing a successful partial scan.
+Obsidian uses the shared namespace and comparison helpers while retaining its
+Vault APIs and existing alias-guard policy. The [developer guide](../../devs.md#file-path-handling)
+links the Commonlib design and ADR. This extraction does not change Metadata
+IDs, defaults, database migration, or the host support matrix below.
+
 ## Scope
 
 | Area | Contract |