Support .env.local override in run_local.sh for developer-specific configurations

scripts/run_local.sh

@@ -21,15 +21,20 @@ esac
 
 WEB_DIR=web
 
+# `.env.local` first: dotenv-cli loads the files in order and never overwrites an already-set
+# variable, so the first file listed wins. That makes `.env.local` the per-developer override of the
+# shared `.env`, matching Next.js' own precedence. A missing file is silently skipped.
+DOTENV_FILES=(-e .env.local -e .env)
+
 if [ "$ENVIRONMENT" = "prod" ]; then
-  npx dotenv -e .env -- npx concurrently \
+  npx dotenv "${DOTENV_FILES[@]}" -- npx concurrently \
     -n API,NEXT,TS \
     -c white,magenta,cyan \
     "cross-env ENVIRONMENT=$NEXT_ENV yarn --cwd=backend/api prod" \
     "cross-env NEXT_PUBLIC_FIREBASE_ENV=$NEXT_ENV yarn --cwd=$WEB_DIR serve" \
     "cross-env yarn --cwd=$WEB_DIR ts-watch"
 else
-  npx dotenv -e .env -- npx concurrently \
+  npx dotenv "${DOTENV_FILES[@]}" -- npx concurrently \
     -n API,NEXT \
     -c white,magenta \
     "cross-env ENVIRONMENT=$NEXT_ENV yarn --cwd=backend/api dev" \