revert: restore code fallbacks for config defaults

This reverts commit 153fc21. With no fallback in code, the deploy
crash-looped: Coolify keeps an entry for every variable compose.yml has
referenced, and empty entries appear to reach the containers as empty
values instead of the compose defaults.

renderer/package.json

@@ -7,8 +7,8 @@
     "node": ">=24 <25"
   },
   "scripts": {
-    "dev": "node --env-file-if-exists=.env --watch src/server.js",
-    "start": "node --env-file-if-exists=.env src/server.js",
+    "dev": "node --watch src/server.js",
+    "start": "node src/server.js",
     "lint": "eslint .",
     "typecheck": "tsc --noEmit",
     "test": "vitest run",