feat(04-02): implement /ask command for single model queries

Create discussion.py with ask_command handler that:
- Validates model name against MODEL_MAP
- Shows usage when called without arguments
- Sends typing indicator while waiting for AI
- Returns formatted response with model name
- Includes optional project context if project is selected

Register CommandHandler("ask", ask_command) in handlers/__init__.py.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/moai/bot/handlers/__init__.py

@@ -7,6 +7,7 @@ project management, discussion commands, and export functionality.
 from telegram.ext import Application, CommandHandler
 
 from moai.bot.handlers.commands import help_command, start_command
+from moai.bot.handlers.discussion import ask_command
 from moai.bot.handlers.projects import project_command, projects_command
 from moai.bot.handlers.status import status_command
 
@@ -27,3 +28,6 @@ def register_handlers(app: Application) -> None:
     # Project management
     app.add_handler(CommandHandler("projects", projects_command))
     app.add_handler(CommandHandler("project", project_command))
+
+    # Discussion / Q&A
+    app.add_handler(CommandHandler("ask", ask_command))

src/moai/bot/handlers/discussion.py

@@ -0,0 +1,58 @@
+"""Discussion handlers for MoAI bot."""
+
+from telegram import Update
+from telegram.ext import ContextTypes
+
+from moai.bot.handlers.projects import get_selected_project
+from moai.core.ai_client import MODEL_MAP, get_ai_client
+
+
+async def ask_command(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
+    """Handle /ask <model> <question> command.
+
+    Examples:
+        /ask claude What is Python?
+        /ask gpt Explain async/await
+    """
+    args = context.args or []
+
+    if len(args) < 2:
+        available = ", ".join(MODEL_MAP.keys())
+        await update.message.reply_text(
+            f"Usage: /ask <model> <question>\n"
+            f"Available models: {available}\n\n"
+            f"Example: /ask claude What is Python?"
+        )
+        return
+
+    model_name = args[0].lower()
+    question = " ".join(args[1:])
+
+    # Validate model
+    if model_name not in MODEL_MAP:
+        available = ", ".join(MODEL_MAP.keys())
+        await update.message.reply_text(f"Unknown model: {model_name}\nAvailable: {available}")
+        return
+
+    # Get project context if available (optional for /ask)
+    project = await get_selected_project(context)
+    project_context = f"Project: {project.name}\n" if project else ""
+
+    # Send "typing" indicator while waiting for AI
+    await update.message.chat.send_action("typing")
+
+    try:
+        client = get_ai_client()
+        response = await client.complete(
+            model=model_name,
+            messages=[{"role": "user", "content": question}],
+            system_prompt=f"{project_context}You are a helpful AI assistant.",
+        )
+
+        # Format response with model name
+        await update.message.reply_text(
+            f"*{model_name.title()}:*\n\n{response}",
+            parse_mode="Markdown",
+        )
+    except Exception as e:
+        await update.message.reply_text(f"Error: {e}")