feat: Add full i18n support to Smart Mind Map plugin

- Consolidated smart_mind_map.py and smart_mind_map_cn.py into a single file.
- Added TRANSLATIONS dictionary supporting 18 languages (en-US, ko-KR, fr-FR, es-AR, en-CA, fr-CA, ja-JP, de-DE, zh-HK, it-IT, zh-CN, en-GB, es-MX, id-ID, es-ES, de-AT, en-AU, vi-VN, zh-TW).
- Implemented automatic language detection with fallback to browser/local storage.
- Added localized date formatting for various locales.
- Added explicit support for zh-TW (Traditional Chinese) with correct translations.
- Updated HTML/JS templates to use injected translations.
- Restored clickable "Markmap" link in the footer for all languages.
- Fixed SyntaxWarning in regex strings by properly escaping backslashes in standard strings.
- Implemented robust UI translation loading to prevent crashes on missing keys.
- Verified frontend rendering with Playwright and backend logic with unit tests.

Co-authored-by: Fu-Jie <33599649+Fu-Jie@users.noreply.github.com>

plugins/actions/smart-mind-map/smart_mind_map.py

@@ -810,7 +810,7 @@ CONTENT_TEMPLATE_MINDMAP = """
         <script type="text/template" id="markdown-source-{unique_id}">{markdown_syntax}</script>
 """
 
-SCRIPT_TEMPLATE_MINDMAP = r"""
+SCRIPT_TEMPLATE_MINDMAP = """
     <script>
       (function() {
         const uniqueId = "{unique_id}";
@@ -852,7 +852,7 @@ SCRIPT_TEMPLATE_MINDMAP = r"""
                 return (0.2126 * r + 0.7152 * g + 0.0722 * b) / 255;
             }
             // rgb(r, g, b) or rgba(r, g, b, a)
-            m = colorStr.match(/rgba?\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)/i);
+            m = colorStr.match(/rgba?\\s*\\(\\s*(\\d+)\\s*,\\s*(\\d+)\\s*,\\s*(\\d+)/i);
             if (m) {
                 const r = parseInt(m[1], 10);
                 const g = parseInt(m[2], 10);
@@ -2017,20 +2017,14 @@ class Action:
             # Prepare content components
             # Resolve translations for UI
             ui_trans = {}
-            target_lang = user_language
-            if target_lang not in TRANSLATIONS and target_lang in self.fallback_map:
-                 target_lang = self.fallback_map[target_lang]
-            if target_lang not in TRANSLATIONS:
-                 target_lang = "en-US"
-
-            full_trans = TRANSLATIONS.get(target_lang, TRANSLATIONS["en-US"])
-            for k in full_trans:
+            # Iterate over base language keys to ensure no missing placeholders
+            for k in TRANSLATIONS["en-US"]:
                 if k.startswith("ui_"):
-                    # For ui_footer which has {year}
+                    val = self._get_translation(user_language, k)
                     if k == "ui_footer":
-                        ui_trans[f"t_{k}"] = full_trans[k].format(year=current_year)
+                        ui_trans[f"t_{k}"] = val.format(year=current_year)
                     else:
-                        ui_trans[f"t_{k}"] = full_trans[k]
+                        ui_trans[f"t_{k}"] = val
 
             content_html = (
                 CONTENT_TEMPLATE_MINDMAP.format(