Update docs, fix Pygame window, and improve camera stage timing

.opencode/skills/mainline-display/SKILL.md

@@ -19,7 +19,14 @@ All backends implement a common Display protocol (in `engine/display/__init__.py
 
 ```python
 class Display(Protocol):
-    def show(self, buf: list[str]) -> None:
+    width: int
+    height: int
+    
+    def init(self, width: int, height: int, reuse: bool = False) -> None:
+        """Initialize the display"""
+        ...
+    
+    def show(self, buf: list[str], border: bool = False) -> None:
         """Display the buffer"""
         ...
     
@@ -27,7 +34,11 @@ class Display(Protocol):
         """Clear the display"""
         ...
     
-    def size(self) -> tuple[int, int]:
+    def cleanup(self) -> None:
+        """Clean up resources"""
+        ...
+    
+    def get_dimensions(self) -> tuple[int, int]:
         """Return (width, height)"""
         ...
 ```
@@ -37,8 +48,8 @@ class Display(Protocol):
 Discovers and manages backends:
 
 ```python
-from engine.display import get_monitor
-display = get_monitor("terminal")  # or "websocket", "sixel", "null", "multi"
+from engine.display import DisplayRegistry
+display = DisplayRegistry.create("terminal")  # or "websocket", "null", "multi"
 ```
 
 ### Available Backends
@@ -47,9 +58,9 @@ display = get_monitor("terminal")  # or "websocket", "sixel", "null", "multi"
 |---------|------|-------------|
 | terminal | backends/terminal.py | ANSI terminal output |
 | websocket | backends/websocket.py | Web browser via WebSocket |
-| sixel | backends/sixel.py | Sixel graphics (pure Python) |
 | null | backends/null.py | Headless for testing |
 | multi | backends/multi.py | Forwards to multiple displays |
+| moderngl | backends/moderngl.py | GPU-accelerated OpenGL rendering (optional) |
 
 ### WebSocket Backend
 
@@ -68,9 +79,11 @@ Forwards to multiple displays simultaneously - useful for `terminal + websocket`
 3. Register in `engine/display/__init__.py`'s `DisplayRegistry`
 
 Required methods:
-- `show(buf: list[str])` - Display buffer
+- `init(width: int, height: int, reuse: bool = False)` - Initialize display
+- `show(buf: list[str], border: bool = False)` - Display buffer
 - `clear()` - Clear screen
-- `size() -> tuple[int, int]` - Terminal dimensions
+- `cleanup()` - Clean up resources
+- `get_dimensions() -> tuple[int, int]` - Get terminal dimensions
 
 Optional methods:
 - `title(text: str)` - Set window title
@@ -81,6 +94,5 @@ Optional methods:
 ```bash
 python mainline.py --display terminal  # default
 python mainline.py --display websocket
-python mainline.py --display sixel
-python mainline.py --display both      # terminal + websocket
+python mainline.py --display moderngl  # GPU-accelerated (requires moderngl)
 ```