feat: various improvements

- add Terms of Service
- add dark mode
- use cards for blog with excerpt

package.json

@@ -1,9 +1,10 @@
 {
+  "$schema": "https://json.schemastore.org/package",
   "name": "felschr.com",
   "version": "1.0.0",
-  "private": true,
   "description": "felschr.com",
   "author": "Felix Schröter",
+  "license": "MIT",
   "keywords": [
     "gatsby"
   ],
@@ -17,16 +18,19 @@
   },
   "dependencies": {
     "@deckdeckgo/highlight-code": "^3.6.0",
-    "@emotion/react": "^11.10.0",
-    "@emotion/styled": "^11.10.0",
+    "@emotion/react": "^11.10.4",
+    "@emotion/styled": "^11.10.4",
     "@mdx-js/mdx": "^1.6.22",
     "@mdx-js/react": "^1.6.22",
+    "@mui/icons-material": "^5.10.6",
+    "@mui/material": "^5.10.8",
     "gatsby": "^4.19.2",
     "gatsby-plugin-emotion": "^7.19.0",
     "gatsby-plugin-image": "^2.19.0",
     "gatsby-plugin-manifest": "^4.19.0",
     "gatsby-plugin-mdx": "^3.19.0",
     "gatsby-plugin-mdx-frontmatter": "^0.0.4",
+    "gatsby-plugin-mdx-source-name": "^1.0.1",
     "gatsby-plugin-react-helmet": "^5.19.0",
     "gatsby-plugin-sharp": "^4.19.0",
     "gatsby-plugin-sitemap": "^5.19.0",