chore: ignore .env.local and .env.*.local

load-env.ts reads .env.local before .env and gives it precedence, so a
developer override file can hold real secrets. Only .env was ignored, so
that file was one 'git add .' away from being committed.

.gitignore

@@ -6,6 +6,8 @@ node_modules.prev/
 .next-staging/
 next-env.d.ts
 .env
+.env.local
+.env.*.local
 *.tsbuildinfo
 src/generated/
 # Runtime avatar/badge imaging disk cache