feat(demo): add pipeline visualization demo mode

- Add --pipeline-demo flag for ASCII pipeline animation
- Create engine/pipeline_viz.py with animated pipeline graphics
- Shows data flow, camera modes, FPS counter
- Run with: python mainline.py --pipeline-demo --display pygame

engine/app.py

@@ -558,6 +558,147 @@ def run_demo_mode():
         print("\n  \033[38;5;245mDemo ended\033[0m")
 
 
+def run_pipeline_demo():
+    """Run pipeline visualization demo mode - shows ASCII pipeline animation."""
+    import time
+
+    from engine import config
+    from engine.camera import Camera, CameraMode
+    from engine.display import DisplayRegistry
+    from engine.effects import (
+        EffectContext,
+        PerformanceMonitor,
+        get_effect_chain,
+        get_registry,
+        set_monitor,
+    )
+    from engine.pipeline_viz import generate_animated_pipeline
+
+    print("  \033[1;38;5;46mMAINLINE PIPELINE DEMO\033[0m")
+    print("  \033[38;5;245mInitializing...\033[0m")
+
+    import effects_plugins
+
+    effects_plugins.discover_plugins()
+
+    registry = get_registry()
+    chain = get_effect_chain()
+    chain.set_order(["noise", "fade", "glitch", "firehose", "hud"])
+
+    monitor = PerformanceMonitor()
+    set_monitor(monitor)
+    chain._monitor = monitor
+
+    display = DisplayRegistry.create("pygame")
+    if not display:
+        print("  \033[38;5;196mFailed to create pygame display\033[0m")
+        sys.exit(1)
+
+    w, h = 80, 24
+    display.init(w, h)
+    display.clear()
+
+    camera = Camera.vertical(speed=1.0)
+
+    effects_to_demo = ["noise", "fade", "glitch", "firehose"]
+    effect_idx = 0
+    effect_name = effects_to_demo[effect_idx]
+    effect_start_time = time.time()
+    current_intensity = 0.0
+    ramping_up = True
+
+    camera_modes = [
+        (CameraMode.VERTICAL, "vertical"),
+        (CameraMode.HORIZONTAL, "horizontal"),
+        (CameraMode.OMNI, "omni"),
+        (CameraMode.FLOATING, "floating"),
+    ]
+    camera_mode_idx = 0
+    camera_start_time = time.time()
+
+    frame_number = 0
+
+    print("  \033[38;5;82mStarting pipeline visualization...\033[0m")
+    print("  \033[38;5;245mPress Ctrl+C to exit\033[0m\n")
+
+    try:
+        while True:
+            elapsed = time.time() - effect_start_time
+            camera_elapsed = time.time() - camera_start_time
+            duration = config.DEMO_EFFECT_DURATION
+
+            if elapsed >= duration:
+                effect_idx = (effect_idx + 1) % len(effects_to_demo)
+                effect_name = effects_to_demo[effect_idx]
+                effect_start_time = time.time()
+                elapsed = 0
+                current_intensity = 0.0
+                ramping_up = True
+
+            if camera_elapsed >= duration * 2:
+                camera_mode_idx = (camera_mode_idx + 1) % len(camera_modes)
+                mode, mode_name = camera_modes[camera_mode_idx]
+                camera = Camera(mode=mode, speed=1.0)
+                camera_start_time = time.time()
+                camera_elapsed = 0
+
+            progress = elapsed / duration
+            if ramping_up:
+                current_intensity = progress
+                if progress >= 1.0:
+                    ramping_up = False
+            else:
+                current_intensity = 1.0 - progress
+
+            for effect in registry.list_all().values():
+                if effect.name == effect_name:
+                    effect.config.enabled = True
+                    effect.config.intensity = current_intensity
+                elif effect.name not in ("hud",):
+                    effect.config.enabled = False
+
+            hud_effect = registry.get("hud")
+            if hud_effect:
+                mode_name = camera_modes[camera_mode_idx][1]
+                hud_effect.config.params["display_effect"] = (
+                    f"{effect_name} / {mode_name}"
+                )
+                hud_effect.config.params["display_intensity"] = current_intensity
+
+            camera.update(config.FRAME_DT)
+
+            buf = generate_animated_pipeline(w, frame_number)
+
+            ctx = EffectContext(
+                terminal_width=w,
+                terminal_height=h,
+                scroll_cam=camera.y,
+                ticker_height=h,
+                camera_x=camera.x,
+                mic_excess=0.0,
+                grad_offset=0.0,
+                frame_number=frame_number,
+                has_message=False,
+                items=[],
+            )
+
+            result = chain.process(buf, ctx)
+            display.show(result)
+
+            new_w, new_h = display.get_dimensions()
+            if new_w != w or new_h != h:
+                w, h = new_w, new_h
+
+            frame_number += 1
+            time.sleep(1 / 60)
+
+    except KeyboardInterrupt:
+        pass
+    finally:
+        display.cleanup()
+        print("\n  \033[38;5;245mPipeline demo ended\033[0m")
+
+
 def main():
     from engine import config
     from engine.pipeline import generate_pipeline_diagram
@@ -566,6 +707,10 @@ def main():
         print(generate_pipeline_diagram())
         return
 
+    if config.PIPELINE_DEMO:
+        run_pipeline_demo()
+        return
+
     if config.DEMO:
         run_demo_mode()
         return