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>

lib/instance/templates/password_settings_panel.html

@@ -1,9 +1,9 @@
-{# 系统设置 · 账户密码（外层 card 由 settings_panel 提供） #}
+{# 系统设置 · 账户密码(外层 card 由 settings_panel 提供) #}
 <h2>账户密码修改</h2>
-<p class="settings-subcard-desc">修改网页登录账号密码，写入 <code>.env</code> 后需重启实例生效。</p>
+<p class="settings-subcard-desc">修改网页登录账号密码,写入 <code>.env</code> 后需重启实例生效.</p>
 <div class="settings-password-form">
     <label>当前密码 <input type="password" id="pwd-old" autocomplete="current-password"></label>
-    <label>新用户名（可选） <input type="text" id="pwd-new-username" autocomplete="username"></label>
+    <label>新用户名(可选) <input type="text" id="pwd-new-username" autocomplete="username"></label>
     <label>新密码 <input type="password" id="pwd-new" autocomplete="new-password"></label>
     <label>确认新密码 <input type="password" id="pwd-confirm" autocomplete="new-password"></label>
 </div>