refactor: extract seed provision scripts to dedicated directory

Move bootstrap, default, and inform scripts from inline template
strings in lib/init.ts to standalone files under seed/, loaded via
an esbuild text-loader plugin. Add type-checking (provisions.d.ts,
tsconfig.json) and ESLint config for the seed scripts. Set tsconfig
module to Preserve to support import attributes.

tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     "lib": ["ES2022", "dom"],
-    "module": "ES2022",
+    "module": "Preserve",
     "moduleResolution": "bundler",
     "target": "ES2022",
     "resolveJsonModule": true,