feat: add Zed editor config for Tailwind CSS

- Create .zed/settings.json to ignore unknown at-rule warnings
- Configure Zed to ignore Tailwind's @tailwind directives
- Add explanatory comment in input.css for Tailwind directives
- Resolves CSS linter warnings in Zed editor

.zed/settings.json

@@ -0,0 +1,14 @@
+{
+  "linter": {
+    "css": {
+      "disabled": ["unknownAtRules"]
+    }
+  },
+  "formatter": {
+    "language": {
+      "CSS": {
+        "unknownAtRules": "ignore"
+      }
+    }
+  }
+}