docs: add ACP and internal systems implementation guides

- add ACP user and developer docs covering setup, lifecycle, callbacks,
  permissions, tool rendering, and runtime behavior
- add developer guides for agent loop, provider runtime resolution,
  prompt assembly, context caching/compression, gateway internals,
  session storage, tools runtime, trajectories, and cron internals
- refresh architecture, quickstart, installation, CLI reference, and
  environments docs to link the new implementation pages and ACP support

website/docs/developer-guide/environments.md

@@ -14,6 +14,10 @@ Hermes Agent includes a full environment framework that connects its tool-callin
 
 All three share the same core: an **environment** class that defines tasks, runs an agent loop, and scores the output.
 
+:::info Repo environments vs RL training tools
+The Python environment framework documented here lives under the repo's `environments/` directory and is the implementation-level API for Hermes/Atropos integration. This is separate from the user-facing `rl_*` tools, which operate as an orchestration surface for remote RL training workflows.
+:::
+
 :::tip Quick Links
 - **Want to run benchmarks?** Jump to [Available Benchmarks](#available-benchmarks)
 - **Want to train with RL?** See [RL Training Tools](/user-guide/features/rl-training) for the agent-driven interface, or [Running Environments](#running-environments) for manual execution