feat(template): create `templates/shadcn` with Tailwind + shadcn wrappers

[thopatevijay]

• Add Tailwind setup files (tailwind.config.js, postcss.config.js).

• Add minimal components/FormControls with wrappers: TextInput, NumberInput, AddressInput, Toggle, Select, Button.

• Add ui/index.ts to export shadcn primitives (or shims).

• Add package.json that includes dependencies required by generated app.

Acceptance criteria

• Template folder can be copied into a target project and yarn & yarn dev would not fail due to missing template files (real install not required at this stage).

• Templates render properly for sample IR (no missing import paths).