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

mise.toml

@@ -59,5 +59,21 @@ topics-init = "curl -s -d 'init' https://ntfy.sh/klubhaus_terminal_mainline_cc_c
 
 pre-commit = "hk run pre-commit"
 
+# =====================
+# Diagrams
+# =====================
+
+# Render Mermaid diagrams to ASCII art
+diagram-ascii = "python3 scripts/render-diagrams.py docs/ARCHITECTURE.md"
+
+# Validate Mermaid syntax in docs (check all diagrams parse)
+# Note: classDiagram not supported by mermaid-ascii but works in GitHub/GitLab
+diagram-validate = """
+python3 scripts/validate-diagrams.py
+"""
+
+# Render diagrams and check they match expected output
+diagram-check = "mise run diagram-validate"
+
 [env]
 KAGI_API_KEY = "lOp6AGyX6TUB0kGzAli1BlAx5-VjlIN1OPCPYEXDdQc.FOKLieOa7NgWUUZi4mTZvHmrW2uNnOr8hfgv7jMvRQM"