feat: refactor class styles and improve test tolerance

- Create a new `_base.d2` file with class styles for base, person, animated, multiple, enqueue, dispatch, library, and task
- Update `flow-01.d2` to reference the new `_base.d2` file for class styles

Signed-off-by: appleboy <[email protected]>

Author: appleboy

images/_base.d2

@@ -0,0 +1,50 @@
+classes: {
+  base: {
+    style: {
+      bold: true
+      font-size: 28
+    }
+  }
+
+  person: {
+    shape: person
+  }
+
+  animated: {
+    style: {
+      animated: true
+    }
+  }
+
+  multiple: {
+    style: {
+      multiple: true
+    }
+  }
+
+  enqueue: {
+    label: Enqueue Task
+  }
+
+  dispatch: {
+    label: Dispatch Task
+  }
+
+  library: {
+    style: {
+      bold: true
+      font-size: 32
+      fill: PapayaWhip
+      fill-pattern: grain
+      border-radius: 8
+      font: mono
+    }
+  }
+
+  task: {
+    style: {
+      bold: true
+      font-size: 32
+    }
+  }
+}

images/flow-01.d2

@@ -1,55 +1,6 @@
 direction: right
 
-classes: {
-  base: {
-    style: {
-      bold: true
-      font-size: 28
-    }
-  }
-
-  person: {
-    shape: person
-  }
-
-  animated: {
-    style: {
-      animated: true
-    }
-  }
-
-  multiple: {
-    style: {
-      multiple: true
-    }
-  }
-
-  enqueue: {
-    label: Enqueue Task
-  }
-
-  dispatch: {
-    label: Dispatch Task
-  }
-
-  library: {
-    style: {
-      bold: true
-      font-size: 32
-      fill: PapayaWhip
-      fill-pattern: grain
-      border-radius: 8
-      font: mono
-    }
-  }
-
-  task: {
-    style: {
-      bold: true
-      font-size: 32
-    }
-  }
-}
+...@_base
 
 user01: {
   label: User01