Replace AI status message with emoji reactions

Instead of sending/editing a verbose status message, now reacts to the
command message: ⏳ while processing, ✅ on success, ❌ on error.

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

app/commands/builtins.py

@@ -309,26 +309,14 @@ async def ai(ctx: "CommandContext") -> None:
         await ctx.reply(str(exc))
         return
 
-    status = await ctx.reply(
-        "\n".join(
-            [
-                "⏳ AI request started",
-                f"model: {selected_alias}",
-                f"context: {invocation.context_messages} message(s)",
-                "tools: understand_image"
-                if invocation.use_image_understanding
-                else "tools: none",
-                f"prompt: {invocation.prompt[:200]}{'...' if len(invocation.prompt) > 200 else ''}",
-            ]
-        )
-    )
-
-    async def _progress(text: str) -> None:
+    async def _react(emoji: str | None) -> None:
         try:
-            await status.edit_text(text)
+            await ctx.client.send_reaction(ctx.message.chat.id, ctx.message.id, emoji=emoji)
         except Exception:
             pass
 
+    await _react("⏳")
+
     try:
         response = await ai_service.generate(
             ctx,
@@ -338,16 +326,11 @@ async def ai(ctx: "CommandContext") -> None:
                 use_image_understanding=invocation.use_image_understanding,
                 prompt=invocation.prompt,
             ),
-            progress=_progress,
         )
     except (RuntimeError, ValueError) as exc:
-        await _progress(f"❌ {exc}")
+        await _react("❌")
+        await ctx.reply(str(exc))
         return
 
-    final_text = f"✅\n{response.text}"
-    if len(final_text) <= 3900:
-        await _progress(final_text)
-        return
-
-    await _progress("✅ Response ready")
+    await _react("✅")
     await _reply_long(ctx, response.text)