Add background process management with process tool, wait, PTY, and stdin support

New process registry and tool for managing long-running background processes
across all terminal backends (local, Docker, Singularity, Modal, SSH).

Process Registry (tools/process_registry.py):
- ProcessSession tracking with rolling 200KB output buffer
- spawn_local() with optional PTY via ptyprocess for interactive CLIs
- spawn_via_env() for non-local backends (runs inside sandbox, never on host)
- Background reader threads per process (Popen stdout or PTY)
- wait() with timeout clamping, interrupt support, and transparent limit reporting
- JSON checkpoint to ~/.hermes/processes.json for gateway crash recovery
- Module-level singleton shared across agent loop, gateway, and RL

Process Tool (model_tools.py):
- 7 actions: list, poll, log, wait, kill, write, submit
- Paired with terminal in all toolsets (CLI, messaging, RL)
- Timeout clamping with transparent notes in response

Terminal Tool Updates (tools/terminal_tool.py):
- Replaced nohup background mode with registry spawn (returns session_id)
- Added workdir parameter for per-command working directory
- Added check_interval parameter for gateway auto-check watchers
- Added pty parameter for interactive CLI tools (Codex, Claude Code)
- Updated TERMINAL_TOOL_DESCRIPTION with full background workflow docs
- Cleanup thread now respects active background processes (won't reap sandbox)

Gateway Integration (gateway/run.py, session.py, config.py):
- Session reset protection: sessions with active processes exempt from reset
- Default idle timeout increased from 2 hours to 24 hours
- from_dict fallback aligned to match (was 120, now 1440)
- session_key env var propagated to process registry for session mapping
- Crash recovery on gateway startup via checkpoint probe
- check_interval watcher: asyncio task polls process, delivers updates to platform

RL Safety (environments/):
- tool_context.py cleanup() kills background processes on episode end
- hermes_base_env.py warns when enabled_toolsets is None (loads all tools)
- Process tool safe in RL via wait() blocking the agent loop

Also:
- Added ptyprocess as optional dependency (in pyproject.toml [pty] extra + [all])
- Fixed pre-existing bug: rl_test_inference missing from TOOL_TO_TOOLSET_MAP
- Updated AGENTS.md with process management docs and project structure
- Updated README.md terminal section with process management overview

pyproject.toml

@@ -43,6 +43,7 @@ cron = ["croniter"]
 slack = ["slack-bolt>=1.18.0", "slack-sdk>=3.27.0"]
 cli = ["simple-term-menu"]
 tts-premium = ["elevenlabs"]
+pty = ["ptyprocess>=0.7.0"]
 all = [
   "hermes-agent[modal]",
   "hermes-agent[messaging]",
@@ -51,6 +52,7 @@ all = [
   "hermes-agent[dev]",
   "hermes-agent[tts-premium]",
   "hermes-agent[slack]",
+  "hermes-agent[pty]",
 ]
 
 [project.scripts]