fix: exclude all code files from spell checker

Spell checking JSON, JS, and TS files flags normal code identifiers
(url, mkdir, tsc, dirname, etc.) as misspellings. Only check prose.

Author: lilith

.github/actions/spell-check/excludes.txt

@@ -21,7 +21,10 @@ yarn-1.19.0.js$
 (?:^|/)lib/
 (?:^|/)__snapshots__/
 (?:^|/)native/
-^package-lock\.json$
+\.json$
+\.js$
+\.ts$
+(?:^|/)scripts/
 ^\.github/workflows/
 ^\.npmignore$
 ^LICENSE$