feat: feed feature, typescript, remove google, fix errs & warns

gatsby-config.d.ts

@@ -0,0 +1,15 @@
+export interface SiteMetadata {
+  title: string
+  description: string
+  siteUrl: string
+  author: {
+    name: string
+    summary: string
+  }
+  social: {
+    linkedin: string
+  }
+}
+
+export const siteMetadata: SiteMetadata
+export const pathPrefix: string