style: rustfmt the blob-removal code (fix the CI fmt gate)

The blob-removal commit (6b4c4dc) failed CI's fmt gate — long assert! lines
and a doc comment that stock rustfmt wraps. No behaviour change; just
`cargo fmt`. Verified via `nix develop -c cargo fmt --check`.

tests/it/blob_removal_migration.rs

@@ -55,15 +55,24 @@ fn v1_blob_project_migrates_to_text_and_rebuilds() {
     assert_eq!(outcome.migrated_from, Some(1), "v1 project was migrated");
 
     let migrated = fs::read_to_string(root.join("project.yaml")).expect("read migrated");
-    assert!(migrated.contains("version: 2"), "version bumped: {migrated}");
+    assert!(
+        migrated.contains("version: 2"),
+        "version bumped: {migrated}"
+    );
     assert!(
         migrated.contains("{ name: data, type: text }"),
         "blob column rewritten to text: {migrated}"
     );
-    assert!(!migrated.contains("type: blob"), "no blob type remains: {migrated}");
+    assert!(
+        !migrated.contains("type: blob"),
+        "no blob type remains: {migrated}"
+    );
     // The pre-migration original is preserved as a .bak.
     let bak = fs::read_to_string(root.join("project.yaml.v1.bak")).expect("read bak");
-    assert!(bak.contains("type: blob"), "bak keeps the original blob column");
+    assert!(
+        bak.contains("type: blob"),
+        "bak keeps the original blob column"
+    );
 
     // 2. Rebuild from the migrated text (as the runtime forces when a blob
     //    column was converted): the column is now `text` and the row data