chore(sync): replace deprecated HF_HUB_ENABLE_HF_TRANSFER with HF_XET_HIGH_PERFORMANCE

feat(sync): warn when keys live in ephemeral .env on a Space

perf(hermes-sync): change-driven backups (poll/debounce, 60s ceiling)

fix(logs): silence noisy WebUI access log polls + bound on-disk log size

Initial release: HuggingMes + Hermes WebUI integration