Add document authoring template population

[milos-pspdf]

Summary

This PR adds a new example demonstrating template data population for Nutrient Document Authoring SDK, similar to the Web SDK's populateDocumentTemplate functionality.

Features

• Simple placeholder replacement: Replace {{variable}} with data values
• Conditional sections: Show/hide content with {{#condition}}...{{/condition}} and {{^condition}}...{{/condition}}
• Array loops: Duplicate content (especially table rows) with {{#array}}...{{/array}}
• Table row duplication: Supports same-row loop syntax for tables
• Text formatting preservation: Maintains text formatting when duplicating content
• Custom delimiters: Configure delimiter characters and default values

Implementation

• Created a standalone TypeScript library at web/document-authoring-template-population/ with:
• Core templating engine using Document Authoring SDK's programmatic API
• Template parser for identifying placeholders
• Processors for placeholders, conditionals, and loops
• Full example with interactive HTML demo

Code Quality

• All files follow Biome's code quality standards (kebab-case filenames, proper formatting)
• Converted static-only classes to exported functions per Biome requirements
• Added exemptions for pre-existing projects with Biome violations, sorry

[miguelcalderon]

Triage note: This looks like a solid, well-documented contribution — full TypeScript library with template parsing, conditionals, and loops for Document Authoring SDK. It's been open for a month with zero reviews.

Needs someone from Dev Rel or the Web team to review. @milos-pspdf — is this still ready for review?

(Part of stale PR triage: #187)

[miguelcalderon]

@milos-pspdf there are some type and build errors I've found locally. Do you mind if I do some changes directly in the PR, please?