build: add client-side TypeScript compilation pipeline

Adds scripts/build-client.mjs which uses esbuild to compile TypeScript
files in src/scripts/client/ into minified IIFE bundles, then writes
them as TypeScript string-constant modules in src/scripts/generated/.

- Adds build:client npm script; wires it as prebuild and predev hooks
- Adds src/scripts/client/tsconfig.json with DOM lib for IDE support
- Excludes src/scripts/client/ from the root Worker tsconfig to avoid
  DOM type conflicts with the Cloudflare Workers runtime types

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/build-client.mjs

@@ -0,0 +1,51 @@
+#!/usr/bin/env node
+// Compiles client-side TypeScript files with esbuild and writes the result
+// as TypeScript string-constant modules importable by the Cloudflare Worker.
+
+import { build } from 'esbuild';
+import { writeFileSync, mkdirSync } from 'fs';
+import { fileURLToPath } from 'url';
+import { dirname, join } from 'path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, '..');
+
+const entries = [
+  {
+    input: 'src/scripts/client/dashboard.ts',
+    exportName: 'dashboardScript',
+    output: 'src/scripts/generated/dashboard.ts',
+  },
+  {
+    input: 'src/scripts/client/emails-page.ts',
+    exportName: 'emailsPageScript',
+    output: 'src/scripts/generated/emails-page.ts',
+  },
+];
+
+mkdirSync(join(root, 'src/scripts/generated'), { recursive: true });
+
+for (const { input, exportName, output } of entries) {
+  const result = await build({
+    entryPoints: [join(root, input)],
+    bundle: true,
+    minify: true,
+    write: false,
+    target: 'es2020',
+    platform: 'browser',
+    format: 'iife',
+  });
+
+  const code = new TextDecoder().decode(result.outputFiles[0].contents);
+  const content = [
+    '// AUTO-GENERATED by scripts/build-client.mjs — do not edit directly.',
+    '// Source: ' + input,
+    '// Run `npm run build:client` to regenerate.',
+    '/* eslint-disable */',
+    'export const ' + exportName + ' = ' + JSON.stringify(code) + ';',
+    '',
+  ].join('\n');
+
+  writeFileSync(join(root, output), content);
+  console.log('Built:', output);
+}

src/scripts/client/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "extends": "../../../tsconfig.json",
+  "compilerOptions": {
+    "lib": ["ES2021", "DOM"],
+    "types": [],
+    "noEmit": true
+  },
+  "include": ["./**/*"],
+  "exclude": []
+}

tsconfig.json

@@ -17,5 +17,5 @@
     "jsxImportSource": "hono/jsx"
   },
   "include": ["src/**/*"],
-  "exclude": ["node_modules", "dist"]
+  "exclude": ["node_modules", "dist", "src/scripts/client/**/*"]
 }