feat: add ACP (Agent Client Protocol) server for editor integration

Adds full ACP support enabling hermes-agent to work as a coding agent
inside VS Code (via vscode-acp extension), Zed, JetBrains IDEs, and
any ACP-compatible editor.

## New module: acp_adapter/

- server.py: HermesACPAgent implementing all 15 Agent protocol methods
  (initialize, authenticate, new/load/list/fork/resume session, prompt,
  cancel, set mode/model/config, on_connect)
- session.py: Thread-safe SessionManager with per-session AIAgent lifecycle
- events.py: Callback factories translating hermes callbacks to ACP
  session_update notifications (tool_call, agent_thought, agent_message)
- tools.py: Tool kind mapping (20+ tools → read/edit/execute/search/fetch/think)
  and content builders (diffs for file edits, terminal output, text previews)
- permissions.py: Bridges hermes approval_callback to ACP requestPermission
  RPC for dangerous command approval dialogs in the editor
- auth.py: Provider credential verification
- entry.py: CLI entry point with .env loading and stderr logging

## Integration points

- run_agent.py: ACP tool bridge hook in _execute_tool_calls() for
  delegating file/terminal operations to the editor
- hermes_cli/main.py: 'hermes acp' subcommand
- pyproject.toml: [acp] optional dependency, hermes-acp entry point,
  included in [all] extras (auto-installed via install.sh)

## Supporting files

- acp_registry/agent.json: ACP Registry manifest
- acp_registry/icon.svg: Hermes caduceus icon
- docs/acp-setup.md: User-facing setup guide for VS Code, Zed, JetBrains

## Tests

- 41 new tests across 5 test files covering tools, sessions, permissions,
  server lifecycle, and auth
- Full test suite: 2901 passed, 0 failures

## User flow

1. hermes is already installed (install.sh)
2. Install 'ACP Client' extension in VS Code
3. Configure: command='hermes', args=['acp']
4. Chat with Hermes in the editor — diffs, terminals, approval
   dialogs, thinking blocks all rendered natively

pyproject.toml

@@ -53,6 +53,7 @@ pty = [
 honcho = ["honcho-ai>=2.0.1"]
 mcp = ["mcp>=1.2.0"]
 homeassistant = ["aiohttp>=3.9.0"]
+acp = ["agent-client-protocol>=0.8.1,<1.0"]
 yc-bench = ["yc-bench @ git+https://github.com/collinear-ai/yc-bench.git"]
 all = [
   "hermes-agent[modal]",
@@ -67,17 +68,19 @@ all = [
   "hermes-agent[honcho]",
   "hermes-agent[mcp]",
   "hermes-agent[homeassistant]",
+  "hermes-agent[acp]",
 ]
 
 [project.scripts]
 hermes = "hermes_cli.main:main"
 hermes-agent = "run_agent:main"
+hermes-acp = "acp_adapter.entry:main"
 
 [tool.setuptools]
 py-modules = ["run_agent", "model_tools", "toolsets", "batch_runner", "trajectory_compressor", "toolset_distributions", "cli", "hermes_constants"]
 
 [tool.setuptools.packages.find]
-include = ["tools", "hermes_cli", "gateway", "cron", "honcho_integration"]
+include = ["tools", "hermes_cli", "gateway", "cron", "honcho_integration", "acp_adapter", "acp_registry"]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]