Add InvoiceReceipt template and update rendering modes to replace the hardcoded mode:email

[yeabwang]

Summary

Adds a print-ready invoice/receipt template and renders each demo template using its configured mode. Addressing #20

Changes

• Added a document-mode invoice template suitable for PDF generation
• Added document template categorization and mode labels
• Replaced the hardcoded email render mode with per-template configuration

Test Plan

• pnpm build passes
• pnpm test passes
• Tested in Storybook (if UI change)
• Added/updated tests for new behavior

Notes

Any additional context for reviewers.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.50%. Comparing base (743b375) to head (f2b9455).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #45   +/-   ##
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  Coverage   95.50%   95.50%           
=======================================
  Files          31       31           
  Lines        1937     1937           
  Branches      382      382           
=======================================
  Hits         1850     1850           
  Misses         86       86           
  Partials        1        1           

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[ivoIturrieta]

Thanks for the PR! Overall, the implementation looks good. The project builds successfully, all tests pass, and the invoice renders correctly in the demo using Document mode.

I tested the PDF generation workflow shown in the example. When exported as A4, the pagination isn’t clean: the main invoice appears on page 1, the footer moves to a mostly empty page 2, and page 3 is blank.

Since the template is described as print-ready, this pagination issue is worth taking a look at. Otherwise, the invoice component and rendering-mode changes look good.