docs: add release notes for v0.2.6

Merge branch 'dev'

feat: update readme

Enhance custom AI provider management and web UI functionality (#28)

feat(webui): add system logs viewer panel with keyword filtering and i18n support

feat: update Dockerfile and README

feat(docker): add docker-entrypoint.sh with env var support + version routing

fix(provider): use getattr for spec.backend to support nanobot-ai 0.1.4.post5

fix: auto-init config on first run + show all channels regardless of config

fix(webui-only): correctly report channel running status from config

fix(webui-only): show channel status from config when running in --webui-only mode

feat(cli): add --webui-only flag to nanobot webui start

refactor(cli): restructure webui subcommands + fix daemon start command

feat: upgrade to nanobot-ai v0.1.4.post6 + add WeCom channel

Merge branch 'main' into dev