feat(pipeline): Integrate MessageOverlayStage into pipeline construction

- Import MessageOverlayStage in pipeline_runner.py
- Add message overlay stage when preset.enable_message_overlay is True
- Add overlay stage in both initial construction and preset change handler
- Use config.NTFY_TOPIC and config.MESSAGE_DISPLAY_SECS for configuration

engine/app/pipeline_runner.py

@@ -12,6 +12,7 @@ from engine.fetch import fetch_all, fetch_all_fast, fetch_poetry, load_cache, sa
 from engine.pipeline import Pipeline, PipelineConfig, PipelineContext, get_preset
 from engine.pipeline.adapters import (
     EffectPluginStage,
+    MessageOverlayStage,
     SourceItemsToBufferStage,
     create_stage_from_display,
     create_stage_from_effect,
@@ -311,6 +312,21 @@ def run_pipeline_mode(preset_name: str = "demo"):
                 f"effect_{effect_name}", create_stage_from_effect(effect, effect_name)
             )
 
+    # Add message overlay stage if enabled
+    if getattr(preset, "enable_message_overlay", False):
+        from engine.pipeline.adapters import MessageOverlayConfig
+
+        overlay_config = MessageOverlayConfig(
+            enabled=True,
+            display_secs=config.MESSAGE_DISPLAY_SECS
+            if hasattr(config, "MESSAGE_DISPLAY_SECS")
+            else 30,
+            topic_url=config.NTFY_TOPIC if hasattr(config, "NTFY_TOPIC") else None,
+        )
+        pipeline.add_stage(
+            "message_overlay", MessageOverlayStage(config=overlay_config)
+        )
+
     pipeline.add_stage("display", create_stage_from_display(display, display_name))
 
     pipeline.build()
@@ -625,6 +641,23 @@ def run_pipeline_mode(preset_name: str = "demo"):
                             create_stage_from_effect(effect, effect_name),
                         )
 
+                # Add message overlay stage if enabled
+                if getattr(new_preset, "enable_message_overlay", False):
+                    from engine.pipeline.adapters import MessageOverlayConfig
+
+                    overlay_config = MessageOverlayConfig(
+                        enabled=True,
+                        display_secs=config.MESSAGE_DISPLAY_SECS
+                        if hasattr(config, "MESSAGE_DISPLAY_SECS")
+                        else 30,
+                        topic_url=config.NTFY_TOPIC
+                        if hasattr(config, "NTFY_TOPIC")
+                        else None,
+                    )
+                    pipeline.add_stage(
+                        "message_overlay", MessageOverlayStage(config=overlay_config)
+                    )
+
                 # Add display (respect CLI override)
                 display_name = new_preset.display
                 if "--display" in sys.argv: