feat: Extend MiniJinja with sha256, base64 utility filters (#23)

[mikkeldamsgaard]

Closes #23 - Adds sha256, base64_encode, base64_decode MiniJinja template filters in dedicated src/template_funcs.rs module. Integrated into render and seed environments. Includes 16 unit tests, docs/templating.md, and example template. Verify: cargo fmt --check && cargo clippy -- -D warnings && cargo test --all

[Copilot]

Pull request overview

This PR extends MiniJinja templating capabilities by adding three custom utility filters (sha256, base64_encode, base64_decode) to support hashing and encoding operations in templates. The implementation creates a dedicated module for template functions, making it easy to extend with additional utilities in the future.

Changes:

• New src/template_funcs.rs module with SHA-256 hashing and Base64 encoding/decoding filters
• Integration of custom filters into both render and seed template environments
• Comprehensive documentation in docs/templating.md with usage examples and error reference
• Example template demonstrating filter usage and chaining capabilities

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/template_funcs.rs	New module implementing sha256, base64_encode, base64_decode filters with 16 unit tests covering normal operation, edge cases, error handling, and chaining
src/render.rs	Registers custom template filters in the render command's MiniJinja environment
src/seed/mod.rs	Registers custom template filters in the seed command's MiniJinja environment
src/main.rs	Declares the new template_funcs module
Cargo.toml	Adds sha2 0.10 and base64 0.22 dependencies
Cargo.lock	Lock file updates for new dependencies
docs/templating.md	New documentation file explaining all filters with usage patterns, chaining examples, and error reference
examples/template-functions/config.tmpl	Example template demonstrating sha256 and base64 filters in practical use cases
CHANGELOG.md	Documents the new features in the Unreleased section

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