NCL-9487 Support custom local dev host

.gitignore

@@ -28,4 +28,7 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
-.devcontainer/
+.devcontainer/
+
+# local dev TLS certs (mkcert)
+certs/

vite.config.ts

@@ -1,13 +1,32 @@
 import react from '@vitejs/plugin-react';
+import fs from 'node:fs';
 import { defineConfig } from 'vite';
 import tsconfigPaths from 'vite-tsconfig-paths';
 
+/**
+ * Local dev hostname, mapped to 127.0.0.1 in /etc/hosts
+ *
+ * Required to make devel REST API and localhost UI same origin.
+ */
+const DEV_HOST = process.env.VITE_DEV_HOST;
+
+/**
+ * Optional locally-trusted TLS cert (git-ignored):
+ *   mkcert -install
+ *   mkcert -key-file certs/dev-key.pem -cert-file certs/dev-cert.pem <DEV_HOST>
+ */
+const https = fs.existsSync('certs/dev-cert.pem')
+  ? { key: fs.readFileSync('certs/dev-key.pem'), cert: fs.readFileSync('certs/dev-cert.pem') }
+  : undefined;
+
 // https://vitejs.dev/config/
 export default () => {
   return defineConfig({
     plugins: [react(), tsconfigPaths()],
     server: {
       port: 3000,
+      https,
+      ...(DEV_HOST && { host: DEV_HOST, allowedHosts: [DEV_HOST] }),
     },
   });
 };