fix: Drop ChatInterface(type=...), removed in Gradio 6

The Space failed to start with "ChatInterface.__init__() got an unexpected
keyword argument 'type'". The platform installs gradio 6.25.0, which dropped the
argument: messages is the only history format now, which is what respond()
already expects and what ControlAgent.stream takes.

Also verified the rest of the file properly this time rather than shipping it
blind. gradio 6.24 is installed locally, close enough to the Space's 6.25, so
app_space.py now imports end-to-end behind a stub engine: the Blocks construct,
respond() streams three updates for a tool-calling turn, and the footer renders
plots, tool names and sources.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app_space.py

@@ -129,9 +129,11 @@ with gr.Blocks(title="ControlAI", fill_height=True) as demo:
         "local install does not apply here — don't enter anything confidential. The full "
         "app, with its own console, runs on Apple Silicon: see the repository.*"
     )
+    # No `type=` argument: Gradio 6 dropped it, messages is the only format now.
+    # History therefore arrives as [{"role":..., "content":...}], which is what
+    # `respond` expects and what ControlAgent.stream takes.
     gr.ChatInterface(
         fn=respond,
-        type="messages",
         examples=[
             "Design an LQR for A=[[0,1],[-2,-3]], B=[[0],[1]], Q=eye(2), R=1.",
             "What is the phase margin of G(s) = 10/(s(s+1)(s+5))?",