Add README and refine .gitignore

README documents both converters, features (raster/TypeLayer/group/bold),
installation, usage, limitations and calibration notes. .gitignore excludes
Python caches, sample assets and large media files while keeping the TySh
template.

.gitignore

@@ -1,4 +1,20 @@
+# ---- Python ----
+__pycache__/
+*.py[cod]
+*.egg-info/
+.venv/
+venv/
+
+# ---- 大文件素材（可从手机重新获取/重新生成，不入库）----
 samples/
 *.ppl
 *.psd
-__pycache__/
+*.png
+*.img
+*.jpg
+*.jpeg
+
+# ---- 临时文件 ----
+*.tmp
+*.log
+.DS_Store