bug fix: enable extended detectors, module-specified encoding payloads by default

[leondz]

garak.core.yaml had two undesired behaviors:

1. extended detectors=false , should now be true
2. probes.encoding config overrode the defaults in the encoding.EncodingMixin class which had been updated to cover more payloads by default

Verification

• default run uses extended detectors; try python -m garak -m test -p grandma.Win11 - two detectors should run
• encoding probes should have more than 30 inferences with generations=1; try python -m garak -m test -p encoding -g1 and check that scores are out of max _config.run._soft_prompt_probe_cap and not 30.