style: format the repository with prettier

These files were already out of step with the project's Prettier config
before this branch of work; running `pnpm format` finally swept them up.
No semantic changes.

Kept separate from the functional commits so the reformatting does not
bury them in diff noise.

theme/env.d.ts

@@ -1,9 +1,9 @@
-declare module '*.css';
+declare module "*.css"
 
 interface ImportMetaEnv {
-  readonly SSG_MD: boolean;
+  readonly SSG_MD: boolean
 }
 
 interface ImportMeta {
-  readonly env: ImportMetaEnv;
+  readonly env: ImportMetaEnv
 }