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/orchestrator_engine.py

@@ -27,6 +27,7 @@ from config import settings
 from llm_client import complete
 from tools import TOOL_DECLARATIONS, call_tool, get_tools_for_role, CONFIRM_REQUIRED
 import usage_tracker
+import tool_audit
 from persona import _user
 
 logger = logging.getLogger(__name__)
@@ -140,6 +141,7 @@ async def run(
         )
 
     client = genai.Client(api_key=api_key)
+    tool_audit.set_context("gemini", model_name or settings.orchestrator_model)
 
     _confirm_allow = frozenset(confirm_allow or ())
     _confirm_deny = frozenset(confirm_deny or ())