fix: resolve terminal display wobble and effect dimension stability

- Fix TerminalDisplay: add screen clear each frame (cursor home + erase down)
- Fix CameraStage: use set_canvas_size instead of read-only viewport properties
- Fix Glitch effect: preserve visible line lengths, remove cursor positioning
- Fix Fade effect: return original line when fade=0 instead of empty string
- Fix Noise effect: use input line length instead of terminal_width
- Remove HUD effect from all presets (redundant with border FPS display)
- Add regression tests for effect dimension stability
- Add docs/ARCHITECTURE.md with Mermaid diagrams
- Add mise tasks: diagram-ascii, diagram-validate, diagram-check
- Move markdown docs to docs/ (ARCHITECTURE, Refactor, hardware specs)
- Remove redundant requirements files (use pyproject.toml)
- Add *.dot and *.png to .gitignore

Closes #25

scripts/render-diagrams.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+"""Render Mermaid diagrams in markdown files to ASCII art."""
+
+import re
+import subprocess
+import sys
+
+
+def extract_mermaid_blocks(content: str) -> list[str]:
+    """Extract mermaid blocks from markdown."""
+    return re.findall(r"```mermaid\n(.*?)\n```", content, re.DOTALL)
+
+
+def render_diagram(block: str) -> str:
+    """Render a single mermaid block to ASCII."""
+    result = subprocess.run(
+        ["mermaid-ascii", "-f", "-"],
+        input=block,
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode != 0:
+        return f"ERROR: {result.stderr}"
+    return result.stdout
+
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: render-diagrams.py <markdown-file>")
+        sys.exit(1)
+
+    filename = sys.argv[1]
+    content = open(filename).read()
+    blocks = extract_mermaid_blocks(content)
+
+    print(f"Found {len(blocks)} mermaid diagram(s) in {filename}")
+    print()
+
+    for i, block in enumerate(blocks):
+        # Skip if empty
+        if not block.strip():
+            continue
+
+        print(f"=== Diagram {i + 1} ===")
+        print(render_diagram(block))
+
+
+if __name__ == "__main__":
+    main()