feat(pipeline): add unified pipeline architecture with Stage abstraction

- Add engine/pipeline/ module with Stage ABC, PipelineContext, PipelineParams
- Stage provides unified interface for sources, effects, displays, cameras
- Pipeline class handles DAG-based execution with dependency resolution
- PipelinePreset for pre-configured pipelines (demo, poetry, pipeline, etc.)
- Add PipelineParams as params layer for animation-driven config
- Add StageRegistry for unified stage registration
- Add sources_v2.py with DataSource.is_dynamic property
- Add animation.py with Preset and AnimationController
- Skip ntfy integration tests by default (require -m integration)
- Skip e2e tests by default (require -m e2e)
- Update pipeline.py with comprehensive introspection methods

docs/PIPELINE.md

@@ -1,12 +1,41 @@
 # Mainline Pipeline
 
+## Architecture Overview
+
+```
+Sources (static/dynamic) → Fetch → Prepare → Scroll → Effects → Render → Display
+                                     ↓
+                    NtfyPoller ← MicMonitor (async)
+```
+
+### Data Source Abstraction (sources_v2.py)
+
+- **Static sources**: Data fetched once and cached (HeadlinesDataSource, PoetryDataSource)
+- **Dynamic sources**: Idempotent fetch for runtime updates (PipelineDataSource)
+- **SourceRegistry**: Discovery and management of data sources
+
+### Camera Modes
+
+- **Vertical**: Scroll up (default)
+- **Horizontal**: Scroll left
+- **Omni**: Diagonal scroll
+- **Floating**: Sinusoidal bobbing
+- **Trace**: Follow network path node-by-node (for pipeline viz)
+
 ## Content to Display Rendering Pipeline
 
 ```mermaid
 flowchart TD
-    subgraph Sources["Data Sources"]
+    subgraph Sources["Data Sources (v2)"]
+        Headlines[HeadlinesDataSource]
+        Poetry[PoetryDataSource]
+        Pipeline[PipelineDataSource]
+        Registry[SourceRegistry]
+    end
+
+    subgraph SourcesLegacy["Data Sources (legacy)"]
         RSS[("RSS Feeds")]
-        Poetry[("Poetry Feed")]
+        PoetryFeed[("Poetry Feed")]
         Ntfy[("Ntfy Messages")]
         Mic[("Microphone")]
     end
@@ -24,9 +53,10 @@ flowchart TD
     end
 
     subgraph Scroll["Scroll Engine"]
+        SC[StreamController]
         CAM[Camera]
-        NH[next_headline]
         RTZ[render_ticker_zone]
+        Msg[render_message_overlay]
         Grad[lr_gradient]
         VT[vis_trunc / vis_offset]
     end
@@ -44,8 +74,8 @@ flowchart TD
     end
 
     subgraph Render["Render Layer"]
+        BW[big_wrap]
         RL[render_line]
-        TL[apply_ticker_layout]
     end
 
     subgraph Display["Display Backends"]
@@ -57,33 +87,78 @@ flowchart TD
         ND[NullDisplay]
     end
 
+    subgraph Async["Async Sources"]
+        NTFY[NtfyPoller]
+        MIC[MicMonitor]
+    end
+
+    subgraph Animation["Animation System"]
+        AC[AnimationController]
+        PR[Preset]
+    end
+
     Sources --> Fetch
     RSS --> FC
-    Poetry --> FP
+    PoetryFeed --> FP
     FC --> Cache
     FP --> Cache
     Cache --> MB
     Strip --> MB
     Trans --> MB
-    MB --> NH
-    NH --> RTZ
+    MB --> SC
+    NTFY --> SC
+    SC --> RTZ
     CAM --> RTZ
     Grad --> RTZ
     VT --> RTZ
     RTZ --> EC
     EC --> ER
     ER --> EffectsPlugins
-    EffectsPlugins --> RL
+    EffectsPlugins --> BW
+    BW --> RL
     RL --> Display
     Ntfy --> RL
     Mic --> RL
+    MIC --> RL
 
     style Sources fill:#f9f,stroke:#333
     style Fetch fill:#bbf,stroke:#333
+    style Prepare fill:#bff,stroke:#333
     style Scroll fill:#bfb,stroke:#333
     style Effects fill:#fbf,stroke:#333
     style Render fill:#ffb,stroke:#333
-    style Display fill:#bff,stroke:#333
+    style Display fill:#bbf,stroke:#333
+    style Async fill:#fbb,stroke:#333
+    style Animation fill:#bfb,stroke:#333
+```
+
+## Animation & Presets
+
+```mermaid
+flowchart LR
+    subgraph Preset["Preset"]
+        PP[PipelineParams]
+        AC[AnimationController]
+    end
+    
+    subgraph AnimationController["AnimationController"]
+        Clock[Clock]
+        Events[Events]
+        Triggers[Triggers]
+    end
+    
+    subgraph Triggers["Trigger Types"]
+        TIME[TIME]
+        FRAME[FRAME]
+        CYCLE[CYCLE]
+        COND[CONDITION]
+        MANUAL[MANUAL]
+    end
+    
+    PP --> AC
+    Clock --> AC
+    Events --> AC
+    Triggers --> Events
 ```
 
 ## Camera Modes
@@ -94,7 +169,8 @@ stateDiagram-v2
     Vertical --> Horizontal: mode change
     Horizontal --> Omni: mode change
     Omni --> Floating: mode change
-    Floating --> Vertical: mode change
+    Floating --> Trace: mode change
+    Trace --> Vertical: mode change
 
     state Vertical {
         [*] --> ScrollUp
@@ -115,4 +191,9 @@ stateDiagram-v2
         [*] --> Bobbing
         Bobbing --> Bobbing: sin(time) for x,y
     }
+
+    state Trace {
+        [*] --> FollowPath
+        FollowPath --> FollowPath: node by node
+    }
 ```