fix: support Valkey URL schemes

[mcollina]

Summary

• parse valkey:// and valkeys:// database paths like their Redis-compatible equivalents instead of treating them as Unix socket paths
• enable TLS for valkeys:// while preserving explicit TLS options
• document the Valkey URL schemes and retained redis:// / rediss:// compatibility
• add URL parsing, constructor, and TLS transport regression coverage

This also implements the complete URL parsing and test coverage requested by #33.

Validation

• npm run build
• npm run lint (passes with the existing warnings)
• focused unit and TLS tests: 33 passing
• npm test: 434 passing, including package export and tsd checks
• Prettier check for the changed test and utility files

Fixes #63

[melroy89]

Owh hi thank you once again.