chore: add DPP examples

[itsyaasir]

Description of change

Adds new Digital Product Passport real-world examples for both Rust and TypeScript audit-trail examples, based on the IOTA DPP demo scenario. The change also wires the new examples into the example registries and README files, and factors the repeated tagged-role issuance helper into shared example utilities for both Rust and TypeScript.

Links to any relevant issues

None.

Type of change

• Enhancement (a non-breaking change which adds functionality)

How the change has been tested

• cargo check -p examples --example 01_customs_clearance --example 02_clinical_trial --example 03_digital_product_passport
• cargo check -p examples --example 03_digital_product_passport
• npx tsc --project ./examples/tsconfig.node.json --noEmit (from bindings/wasm/audit_trail_wasm)
• npx tsc --project ./examples/tsconfig.web.json --noEmit (from bindings/wasm/audit_trail_wasm)
• cargo fmt --all

Change checklist

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked that new and existing unit tests pass locally with my changes
• I have updated the CHANGELOG.md, if my changes are significant enough