format and add claude hook for formatting

.claude/settings.json

···
+{
+  "hooks": {
+    "PostToolUse": [
+      {
+        "matcher": "Write|Edit|MultiEdit",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "gleam format"
+          }
+        ]
+      }
+    ]
+  }
+}