Add deletePlaylist support to Scala examples for SDK 3.1.0

[wenbinf]

Scala examples still target Java SDK 3.0.0 and do not document permanent playlist deletion. This updates the published dependency to com.listennotes:podcast-api:3.1.0 and generates deletePlaylist examples, the method index, and the contract snapshot for all 31 supported operations.

The README explains that deletion is irreversible, applications should ask users to confirm, and only the playlist's saved references and notes are removed. CI now resolves the published Maven dependency directly on Java 17 and 25. The standalone verification script also works with macOS Bash 3 when no source override is provided.

Validation:

• Java 17 and 25: 33 offline tests, all 32 README examples compile, and application distribution builds.
• Public mock: 32 integration tests covering all 31 operations; no production requests.
• Deletion checks cover path encoding, empty request bodies, missing IDs, response data and headers, caller-map preservation, and 404 errors.
• Standalone verification passes with Maven Central and with the optional Java source override; the resolved Maven JAR matches the verified 3.1.0 release checksum.
• Deterministic generation and sync check; 52 synchronization tests, 25 Django documentation tests, frontend typechecking, and 90 frontend documentation tests pass.

This repository contains Scala examples for the shared Java library; there is no separate Scala Maven package to publish.