fix: resolve clippy warnings and rustfmt issues for CI compliance

Fix all clippy lints (collapsible if, clone on Copy, needless borrow,
redundant bindings, unused params) and apply rustfmt across the codebase.
Update test mocks to match Uuid-based trait signatures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/interfaces/api/handlers/dedup_handler.rs

@@ -99,7 +99,9 @@ impl DedupHandler {
         }
 
         // Only reveal whether THIS user has the blob — no global oracle
-        let user_has_it = dedup.user_owns_blob_reference(&hash, &auth_user.id.to_string()).await;
+        let user_has_it = dedup
+            .user_owns_blob_reference(&hash, &auth_user.id.to_string())
+            .await;
 
         if user_has_it {
             // Fetch size from metadata (safe — user owns a reference)
@@ -346,7 +348,10 @@ impl DedupHandler {
         }
 
         // Verify the user owns at least one file referencing this blob
-        if !dedup.user_owns_blob_reference(&hash, &auth_user.id.to_string()).await {
+        if !dedup
+            .user_owns_blob_reference(&hash, &auth_user.id.to_string())
+            .await
+        {
             return Response::builder()
                 .status(StatusCode::NOT_FOUND)
                 .header(header::CONTENT_TYPE, "application/json")