feat: engine/model in audit log + docs update

- tool_audit: ContextVars (engine, model) set at orchestrator run start; fields added to every entry
- orchestrator_engine: tool_audit.set_context("gemini", model_name) at run() start
- openai_orchestrator: tool_audit.set_context("openai", model label) at run() start
- audit table: Model column between Status and Args
- HELP.md: push notifications section, audit log in Files section, tool count 30→40, new API endpoints
- TODO__Agents.md: web_push and audit log marked complete with full detail

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/openai_orchestrator.py

@@ -26,6 +26,7 @@ from openai import AsyncOpenAI
 from config import settings
 from orchestrator_engine import OrchestrateCheckpoint, OrchestratorResult
 from tools import OPENAI_TOOL_SCHEMAS, call_tool, get_openai_tools_for_role, get_tools_for_role, CONFIRM_REQUIRED
+import tool_audit
 
 logger = logging.getLogger(__name__)
 
@@ -73,6 +74,7 @@ async def run(
     effective_confirm = (CONFIRM_REQUIRED - set(_confirm_allow)) | set(_confirm_deny)
 
     client, model_name, active_tools = _build_client(model_cfg, user_role, tool_list)
+    tool_audit.set_context("openai", model_cfg.get("label") or model_name)
 
     sys_content = (system_prompt or "") + _TOOL_INSTRUCTION
     messages: list[dict] = [{"role": "system", "content": sys_content}]