ACP ignores agent.max_turns and falls back to 90 iterations

Bug description

ACP sessions ignore the configured agent.max_turns value. SessionManager._make_agent() loads config.yaml, but constructs AIAgent(**kwargs) without passing max_iterations. ACP therefore falls back to agent/agent_init.py's constructor default of 90 iterations.

This causes tool-heavy ACP turns to stop at exactly 90 iterations even when hermes config get agent.max_turns reports a higher value.

Reproduction

Environment:

• Hermes Agent v0.20.4 (2026.8.18)
• Native Windows 11
• VS Code ACP Client
• agent.max_turns: 150

Steps:

1. Configure agent.max_turns above 90:

   hermes config set agent.max_turns 150
   hermes config get agent.max_turns
   # 150
   

2. Start a fresh ACP session and run a tool-heavy coding task.

3. Observe the turn stops after exactly 90 assistant messages with finish_reason=tool_calls.

4. Hermes injects:

   You've reached the maximum number of tool-calling iterations allowed. Please provide a final response summarizing what you've found and accomplished so far, without calling any more tools.

Expected behavior

ACP should pass the resolved agent.max_turns value to AIAgent(max_iterations=...), matching CLI behavior.

Actual behavior

acp_adapter/session.py::_make_agent() builds kwargs for AIAgent but omits max_iterations; the configured value is never used.

Current upstream main was checked at 41447a6 and still has the omission.

Proposed fix

Read config["agent"]["max_turns"] from the already-loaded config and include it as max_iterations when constructing the ACP AIAgent:

agent_config = config.get("agent") or {}
configured_max_turns = (
    agent_config.get("max_turns")
    if isinstance(agent_config, dict)
    else None
)

# ... build kwargs ...
if configured_max_turns is not None:
    kwargs["max_iterations"] = configured_max_turns

Add a regression test that monkeypatches load_config() with {"agent": {"max_turns": 150}}, captures the AIAgent constructor kwargs, and asserts max_iterations == 150.

Local verification

The proposed patch was applied locally using TDD:

• Regression test before fix: failed with KeyError: 'max_iterations'
• Regression test after fix: passed
• ACP tests excluding four pre-existing Windows-only POSIX pipe/symlink cases: 127 passed, 4 deselected
• git diff --check: passed
• py_compile: passed

Start in acp_adapter/session.py at SessionManager._make_agent(), then inspect how the already-loaded config is used to build AIAgent kwargs. Add the regression test described in the issue, capturing constructor kwargs with agent.max_turns set to 150 and checking max_iterations. Run the ACP tests and confirm the regression passes without introducing new failures.