Implement Inspect protocol for generated structs to redact PII fields

[claudio-dalicandro]

Problem

When generated Avro structs end up in logs (via Logger, IO.inspect/2, exception messages, etc.), PII-marked fields are displayed in plain text. This is a data privacy concern, IMHO.

Solution

For every record schema that has fields marked with "pii": true, the code generator now produces a defimpl Inspect that replaces PII field values with **REDACTED** in the inspect output. Records without PII fields are not affected — no custom Inspect implementation is generated.

Example

Given a schema with full_name and email marked as PII:

# Before (PII leaked in logs)
#=> %Events.V1.Person{id: "123", full_name: "John Doe", email: "john@example.com", age: 30}

# After (PII redacted)
#=> #PersonWithPii<[id: "123", full_name: "**REDACTED**", email: "**REDACTED**", age: 30]>

[cpiemontese]

If you update the CHANGELOG and run a suite-py bump I'll release after merge 😊