Add receipt-standard template to expand template library

[JesusOmarDev1]

Problem / Motivation

The template library currently has 2 categories (Invoices and Reports) with 7 templates total. There's no representation for common document types like receipts, letters, or contracts. Components like PdfForm, Signature, Card, and KeepTogether aren't showcased in any template, making it harder for users to discover how to use them in real documents.

Proposed Solution

Add new template categories, starting with Receipts. A receipt-standard template would demonstrate a compact purchase receipt (Table, Badge for payment status, KeyValue for totals). This follows the existing template pattern (Document wrapper + ThemeProvider + inner Content component with embedded sample data).

Future categories could include:

Letters (formal correspondence — exercises Heading, Text, Link)
Contracts (NDA/service agreements — exercises PdfForm, Signature, KeepTogether, PageBreak)
Each would include: template source (.tsx), types file (.types.ts), gallery container page, and registry JSON. Happy to implement this — starting with receipts as a first PR.

Alternatives Considered

Could also start with contracts since they exercise the most underrepresented components (PdfForm + Signature), but receipts are simpler and make a better first contribution.

Area

Documentation

Additional Context

Components currently unused in templates: PdfForm, Signature, Card, Heading (standalone), Link, KeepTogether, PageBreak, Stack (standalone). New templates would showcase these and give users ready-to-use starting points.

[akii09]

Hey, thanks for the detailed proposal and for thinking through the scope so clearly - this is exactly the kind of contribution that makes the library more useful! 🙌

Fully agree that templates are the best way to showcase components like PdfForm, Signature, and KeepTogether that are hard to discover otherwise.

Let's do it - starting with receipts.

A few guidelines to keep the PR focused and easy to review:

1. One template per PR - receipts first, letters/contracts as follow-up PRs once this lands
2. Follow the existing template pattern exactly - Document wrapper → ThemeProvider → Content component with embedded sample data, plus a .types.ts file and registry JSON. Pick any existing template as your reference.
3. No new infrastructure — only new files, no changes to the template system itself
4. Run pnpm build:registry before submitting so the registry JSON is up to date

If you're unsure about any part of the structure while building, feel free to drop a comment here or open a draft PR early - happy to give feedback as you go.

Labelling this as good first issue so others can pick it up too if you're no longer interested. First one to open a draft PR gets it! 🚀

[JesusOmarDev1]

Do I need to create a new branch and make the PR or use an existing one?