Fix client IP filtering in get_queries

[DanielVd]

Summary

Fix PiHole6Metrics.get_queries() client filtering by sending the value as the Pi-hole v6 client_ip query parameter.

The public Python argument remains client for backward compatibility, but the HTTP request currently sends it as client. Pi-hole FTL /api/queries expects client_ip for filtering by client address and client_name for filtering by client name, so the existing parameter is ignored for client IP filtering.

Changes

• Keep the existing client Python argument unchanged.
• Send its value as the HTTP client_ip parameter.
• Clarify in the docstring that client represents a client IP.
• Add regression tests covering the parameter mapping and the no-filter case.

Tests

PYTHONPATH=src python3 -m unittest discover -v

Result: 2 tests passed.

This is intentionally scoped to fixing client IP filtering. Support for filtering by client_name can be added separately without changing this fix.

[DanielVd]

Validated directly against a real Pi-hole v6 instance, without going through the MCP layer.

For the same 60-second query window and target client:

• Expected queries for the target client: 1.
• Current pihole6api: 130 queries returned, 129 belonging to other clients.
• Patched pihole6api: 1 query returned, 0 mismatches.

Result: the current client HTTP parameter does not filter the query log, while mapping the existing Python client argument to Pi-hole's client_ip parameter produces exactly the expected result.