docs: add Hermes Agent integration

[PipDscvr]

Summary

• add Hermes Agent overview, Local, and Cloud integration docs
• document native memory provider behavior, tools, config, and troubleshooting
• wire Hermes into integrations overview and sidebar
• keep Local docs mode-aware with PublishedOnly / SourceOnly for ATOMICMEMORY_DOCS_MODE

Validation

• npm run typecheck
• npm run build
• ATOMICMEMORY_DOCS_MODE=published npm run build
• git diff --check