chore: add cost-safe GitHub Codespaces devcontainer

Author: eulicesl

.devcontainer/devcontainer.json

@@ -0,0 +1,30 @@
+{
+  "name": "omi-fork-dev",
+  "image": "mcr.microsoft.com/devcontainers/javascript-node:22-bookworm",
+  "hostRequirements": {
+    "cpus": 2,
+    "memory": "8gb",
+    "storage": "32gb"
+  },
+  "features": {
+    "ghcr.io/devcontainers/features/github-cli:1": {},
+    "ghcr.io/devcontainers/features/python:1": {
+      "version": "3.12"
+    }
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "dbaeumer.vscode-eslint",
+        "ms-python.python"
+      ]
+    },
+    "codespaces": {
+      "openFiles": [
+        "README.md",
+        "AGENTS.md"
+      ]
+    }
+  },
+  "postCreateCommand": "npm install || true"
+}