openai-consumer: the static-key model-access consumer (ADR 0050)

The consumer half of the OTHER model-access shape. Where anthropic-consumer
receives a refreshed access token, this receives one operator-supplied API key
the mesh sealed to it and the host unsealed at its secret path — no manager, no
refresh, no usage. It writes the key where an OpenAI/Codex client reads it: an
OPENAI_API_KEY env file and the publicly-known Codex auth.json. Pure node, no
SDK import — the simplest a model-access consumer gets.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

modules/openai-consumer/tsconfig.json

@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "noEmit": true
+  },
+  "include": [
+    "credentials.ts",
+    "apply/index.ts"
+  ]
+}