Refactor agent execution to use AgentRun with OpenAI-compatible API

Major refactoring to support isolated run objects with streaming, events, and OpenAI-compatible endpoints.

## Backend Changes

- **Agent class**: Added `run()` method, `received_message()` wraps chat into AgentRun
- **AgentRun class**: New class for run state with event system, serialization, and user tracking
- **inference.py**: Complete refactor with `build_messages()`, `chat_completion()`, tool support for llama-cpp/ollama/replicate
- **tools.py**: New centralized tool management (ToolSpec, ToolParameter, format_tools_for_engine)
- **tools.py**: Removed legacy Toolset/Action/ToolDescription system
- **server.py**: Added OpenAI-compatible `/api/openai/v1/chat/completions` endpoint with streaming support
- **temporary.py**: Added `self.runs` dict to State class
- **expert.py**: Refactored to use new Agent.run() signature
- **scripted.py**: Updated to raise NotImplementedError

## Frontend Changes

- **backend.js**: Added `onRunEvents()` for run event subscriptions
- **Sidebar.vue**: Added runs navigation mode
- **router/index.js**: Renamed User route to RunsView
- **RunsView.vue**: New view for listing/monitoring agent runs

## Breaking Changes

- Agent `prompt()` signature changed: `(instruction, input=None, **kwargs)` instead of `(content)`
- Agent `received_message()` must use AgentRun pattern
- Tools.py removed, functionality moved to tool.py
- Deprecated tool prompt/action system removed

backend/src/temporary.py

@@ -1,4 +1,7 @@
 
+from datetime import datetime
+import time
+
 def generate_tmp_id(app):
     app.tmp.id_counter += 1
     return "tmp-" + str(app.tmp.id_counter)
@@ -12,6 +15,7 @@ class State:
         self.agents = {}
         self.chats = {}
         self.threads = {}
+        self.runs = {}
 
         # list of temporary agent ids that belong to a real user
         self.user_agents = {}