dotenv support (#122)

Signed-off-by: Aron Jones <aron.jones@gmail.com>

codex-cli/package-lock.json

@@ -12,6 +12,7 @@
         "@inkjs/ui": "^2.0.0",
         "chalk": "^5.2.0",
         "diff": "^7.0.0",
+        "dotenv": "^16.1.4",
         "file-type": "^20.1.0",
         "ink": "^5.2.0",
         "ink-select-input": "^6.0.0",
@@ -2435,6 +2436,17 @@
         "node": ">=6.0.0"
       }
     },
+    "node_modules/dotenv": {
+      "version": "16.5.0",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-16.5.0.tgz",
+      "integrity": "sha512-m/C+AwOAr9/W1UOIZUo232ejMNnJAJtYQjUbHoNTBNTJSvqzzDh7vnrei3o3r3m9blf6ZoDkvcw0VmozNRFJxg==",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",