Add community license and verified hardware scope

[Hrabovszki1023]

Summary

• add the Pylontech Console Community License for free private, academic and other non-commercial use
• require a separate commercial license for commercial products, services, installations, support, internal business use, forks and derived works
• describe the verified five-module mixed rack: two US2000 and three US2000C modules with 15 cells each
• document the tested Waveshare RS232/485/422 TO POE ETH (B), Proxmox-hosted Docker deployment, linux/amd64 image and ioBroker MQTT integration
• state explicit compatibility limits for unverified batteries, gateways, protocols and architectures
• replace the outdated README implementation status and use the accurate term source-available

Verification

• PYTHONPATH=src python -m pytest -q — 207 passed
• python -m ruff check . — passed
• python -m mypy src tests — passed
• git diff --check — passed

Notes

This is intentionally not an OSI Open Source license because commercial use requires a separate agreement. The hardware statement documents observed monitoring compatibility and does not replace Pylontech installation requirements or approve arbitrary mixed battery configurations.