build: add solution and client bundling scripts

scripts/copy-client.mjs

@@ -0,0 +1,18 @@
+import { cpSync, existsSync, mkdirSync, rmSync } from 'node:fs'
+import { dirname, join, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+
+const root = resolve(dirname(fileURLToPath(import.meta.url)), '..')
+const source = join(root, 'client', 'dist')
+const target = join(root, 'backend', 'wwwroot')
+
+if (!existsSync(source)) {
+  console.error(`[copy] Build output not found: ${source}. Run "npm run build" in client first.`)
+  process.exit(1)
+}
+
+rmSync(target, { recursive: true, force: true })
+mkdirSync(target, { recursive: true })
+cpSync(source, target, { recursive: true })
+
+console.log(`[copy] Copied ${source} -> ${target}`)