release: v1.7.0 - region-agnostic skeleton, selectable true-black, English code

Highlights:

- minimum mode: add min_true_black switch (default True = unchanged v1.6.1 behaviour).

  True  : true-black gate + CC denoise (best for black line work).

  False : no gate, keeps colored regions, distance-transform thinning

          (best for colorful posters).

- skeleton mode: replace hue-specific green-block smoothing with

  saturation-based _color_zones; no hue or side-of-image assumptions.

- Move all comments, docstrings and messages to English.

- Remove built-in default paths; examples/demo.py now requires args.

- README: document both minimum variants, resolution guidance, parameters.

- tests: 18 cases covering I/O, both modes, both minimum variants.

.gitignore

@@ -10,29 +10,29 @@ dist/
 .eggs/
 pip-wheel-metadata/
 
-# 虚拟环境
+# Virtual environments
 .venv/
 venv/
 env/
 ENV/
 
-# 测试 / 缓存
+# Tests / caches
 .pytest_cache/
 .coverage
 htmlcov/
 .tox/
 .mypy_cache/
 
-# IDE
+# IDEs
 .idea/
 .vscode/
 *.swp
 
-# 输出
+# Outputs
 output/
 *.log
 
-# 系统
+# OS
 .DS_Store
 Thumbs.db
 desktop.ini