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

frontend/src/backend.js

@@ -30,6 +30,7 @@ let credentialsDeferred = createDeferred();
 const pendingActions = {}; // Maps nonce to { resolve, reject }
 const chatListeners = {}; // Maps chatId to an array of callback functions
 const orphanHandlers = []; // Queue of callbacks for orphan server messages
+const runListeners = []; // Queue of callbacks for run events
 
 function createDeferred() {
   let resolve, reject;
@@ -191,6 +192,15 @@ function handleIncomingMessage(rawData) {
     } else {
       console.log(`No active listeners for chatId ${chatId}`);
     }
+  } else if (packet.action == 'run-event') {
+    // Broadcast run events to all listeners
+    runListeners.forEach(callback => {
+      try {
+        callback(packet);
+      } catch (e) {
+        console.error(`Error in run event listener:`, e);
+      }
+    });
   } else {
     if (orphanHandlers.length) {
       const f = orphanHandlers.shift();
@@ -247,6 +257,22 @@ export function onChatMessages(chatId, callback) {
   };
 }
 
+export function onRunEvents(callback) {
+  if (typeof callback !== 'function') {
+    throw new TypeError("onRunEvents: callback must be a function.");
+  }
+
+  runListeners.push(callback);
+
+  // Return an unsubscribe function
+  return () => {
+    const index = runListeners.indexOf(callback);
+    if (index > -1) {
+      runListeners.splice(index, 1);
+    }
+  };
+}
+
 export async function getChats() {
   if (cache.chats === null) {
     const response = await sendAction("get-chats", {});