Add nullable unique presets

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@endeavorance/prequel",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "exports": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "scripts": {

src/column-presets.ts

@@ -66,6 +66,42 @@ export const ColumnOf = {
         cascade,
       };
     },
+
+    Unique: {
+      Text: {
+        type: "TEXT",
+        nullable: true,
+        unique: true,
+      },
+
+      Int: {
+        type: "INTEGER",
+        nullable: true,
+        unique: true,
+      },
+
+      Real: {
+        type: "REAL",
+        nullable: true,
+        unique: true,
+      },
+
+      Blob: {
+        type: "BLOB",
+        nullable: true,
+        unique: true,
+      },
+
+      ForeignKey(otherTable: Table<unknown>, cascade = false): ColumnShorthand {
+        return {
+          type: otherTable.primaryColumnType(),
+          references: otherTable.reference(),
+          nullable: true,
+          unique: true,
+          cascade,
+        };
+      },
+    },
   },
 
   Unique: {