Desktop sessions (via 'hermes serve' -> TUI gateway) never set
HERMES_TUI_CHECKPOINTS, so agent creation gated filesystem checkpoints on
that env var alone: checkpoints.enabled: true in config.yaml was silently
ignored on the desktop surface while the CLI and messaging gateway honored
it. _make_agent now resolves enablement via the new topical sibling
tui_gateway/checkpoints.py: the env var (explicit '--tui --checkpoints'
opt-in) wins when present, otherwise fall back to the checkpoints config
section with DEFAULT_CONFIG defaults, mirroring gateway/run.py
_checkpoint_agent_kwargs. The pure _resolve_checkpoint_hash moves to the
same sibling to offset the facade's line cap.
Reimplements https://github.com/NousResearch/hermes-agent/pull/79743 by
@thatssoheil (its branch pre-dates current main and no longer applies);
test coverage carried over from that PR.
a6b65df5bd