chunk command only accepts .wav despite extract supporting many formats

[dennisthemenacing]

Problem

The command and have an inconsistency: accepts , , , , , and files, but the command and only accept .

This means a user can extract from a but can't chunk it afterwards without first converting to .

Scope

1. Update in to accept the same formats as (, , , , , ) using 's format auto-detection.
2. Update validation to match.
3. Update the MCP tool if needed (it delegates to ).
4. Add a test covering non-wav input to .

Acceptance

• works without manual conversion.
• All existing chunk tests pass.
• Docs in are updated to list supported formats.