tech-debt(audio): API naming consistency + deprecation plan

[morozsm]

Why

Audio APIs now mix low-level and high-level concepts; naming should be consistent and migration predictable.

Scope

• Define canonical naming for low-level vs high-level audio methods
• Add deprecation warnings where needed
• Publish migration notes

Acceptance Criteria

• Clear naming map documented
• Deprecation warnings in place
• Backward compatibility preserved through deprecation window