Normalize fullwidth punctuation to ASCII across codebase.

Add scripts/normalize_ambiguous_unicode.py; fix corrupted patch_instance_theme_templates.py. Preserves curly quotes in string literals; removes Git homoglyph warnings on .env.example.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/generate_brand_icons.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""生成品牌 PNG/ICO（Pillow），供 Chrome 快捷方式与 manifest 使用。"""
+"""生成品牌 PNG/ICO(Pillow),供 Chrome 快捷方式与 manifest 使用."""
 from __future__ import annotations
 
 import os
@@ -35,7 +35,7 @@ def render_icon(size: int):
     inner = m + max(2, size // 28)
     _rounded_rect(draw, (inner, inner, size - inner, size - inner), max(6, r - 4), PANEL)
 
-    # 渐变描边（四角采样）
+    # 渐变描边(四角采样)
     border = max(2, size // 42)
     for i in range(border):
         t0 = i / max(1, border - 1)