init: WordFileParse docx→HTML 解析服务（含 Word EQ 域公式修复）

服务：Spring Boot 3.2 + docx4j 8.3.9，POST /api/v3/server_office_file/file/parse
      接受 .docx，返回 HTML（公式 → LaTeX，图片 → RustFS 外链）

公式支持三类来源：
- OMML（Word 2007+ 公式）      → Python omml_mathml2latex
- MathType OLE 对象            → Ruby mathtype2mathml → MathML → LaTeX
- Word EQ 域（老教辅主力）      → EqToLatexUtil（本次新增）

本次改动：
1. 新增 java-svc/.../core/EqToLatexUtil.java：
   移植自 jby backend-services office-core，EQ 语法 → LaTeX
   （\f→\dfrac、\r→\sqrt、\i→\int/\sum/\prod、\s→^{}/_{}、\b→\left\right、
     \a→array、\x→\boxed/\overline、\o\al 堆叠、圈码、化学符号、极限、连等式）
   品牌标记 JBYU* → WPU*，与采集端一致
2. CtoMathFinder：接上 EQ 分支（原为 not-ported 桩），域代码经
   EqToLatexUtil.convert 转 LaTeX 写入 eqLatexMap（WPEQNUM 占位符）
3. WordParseUtil.dealPlaceholder：EQ 的 LaTeX 同样加 \( \) 包裹
   （原先因 WPEQNUM 例外不加包裹，前端/MathJax 不渲染）

修前症状：教辅 Word 里分式/方程组/上下标整段丢失（如 {−1/3, 1} 变成 {－，1}）
修后实测：46 份教辅 2908 处 EQ 域全部还原，公式总数 2954 处、零未包裹残留

安全：application.yml（含 RustFS 密钥）不入库，提供 application.yml.example；
      OssService 的 @Value 默认密钥已清空

scripts/omml_mathml2latex/visitors/mn_visitor.py

@@ -0,0 +1,136 @@
+"""
+Visitor for <mn> (number) MathML elements.
+
+The <mn> element represents numeric literals in MathML, including:
+- Integers (1, 2, 3, ...)
+- Decimals (3.14, 2.718, ...)
+- Scientific notation (1.5×10⁻³)
+- Fractions in decimal form (0.5)
+"""
+
+from lxml import etree as ET
+from ..core.interfaces import Visitor, Strategy
+from ..utils import text_content as _text_content, convert_spaces_to_latex, escape_latex_special_chars
+from ..data import CHEMICAL_ELEMENTS, COMMON_UNITS
+from ..converters.post_processor import PostProcessor
+
+
+class MnVisitor(Visitor):
+    """
+    Handles <mn> (number) MathML elements.
+
+    This visitor converts numbers to LaTeX format. Most numbers
+    are returned as-is, but the strategy can customize formatting
+    for specific subjects (e.g., chemistry, physics).
+
+    Examples:
+        Standard numbers:
+            <mn>123</mn> → 123
+            <mn>3.14</mn> → 3.14
+            <mn>0.5</mn> → 0.5
+
+        Scientific notation (handled at operator level):
+            <mn>1.5</mn><mo>×</mo><mn>10</mn><msup><mn>-3</mn></msup>
+            → 1.5 \\times 10^{-3}
+    """
+
+    def __init__(self, strategy: Strategy):
+        """
+        Initialize the Mn visitor.
+
+        Args:
+            strategy: The formatting strategy to use
+        """
+        super().__init__(strategy)
+        self._converter_context = None
+
+    def set_converter_context(self, converter):
+        """Set converter context for color suppression checking."""
+        self._converter_context = converter
+
+    def visit(self, node: ET.Element) -> str:
+        """
+        Convert <mn> element to LaTeX.
+
+        Args:
+            node: The <mn> element to convert
+
+        Returns:
+            LaTeX string representation
+
+        Raises:
+            ValueError: If node is not an <mn> element
+        """
+        if not self.can_handle(node):
+            raise ValueError(f"MnVisitor cannot handle element '{node.tag}'")
+
+        # Get text content
+        content = _text_content(node)
+
+        # Handle empty content
+        if not content:
+            return ""
+
+        # Escape LaTeX special characters before any other processing
+        content = escape_latex_special_chars(content)
+
+        # Handle spaces (NBSP → ~, space → \ )
+        if '\xa0' in content or ' ' in content:
+            converted = convert_spaces_to_latex(content)
+
+            # If content was ONLY spaces, return directly
+            if not content.strip():
+                return self._wrap_with_color(converted, node)
+
+            # Update content with converted spaces
+            content = converted
+
+        # Delegate to strategy for subject-specific number formatting
+        result = self.strategy.format_number(content, node)
+
+        return self._wrap_with_color(result, node)
+
+    def _wrap_with_color(self, latex: str, node: ET.Element) -> str:
+        """
+        Wrap LaTeX with color command if node has color attribute.
+
+        Args:
+            latex: The LaTeX string to wrap
+            node: The element node
+
+        Returns:
+            LaTeX string, optionally wrapped with color command
+        """
+        # Use the centralized color wrapping utility with suppression support
+        from ..utils.color_helpers import wrap_element_with_color
+
+        # Get converter context from multiple sources (for backward compatibility):
+        # 1. Direct visitor context (set by legacy_adapter)
+        # 2. Strategy context (shared across all visitors, including child visitors)
+        context = getattr(self, '_converter_context', None)
+        if context is None and hasattr(self.strategy, '_converter_context'):
+            context = self.strategy._converter_context
+        
+        return wrap_element_with_color(latex, node, context)
+
+    def can_handle(self, node: ET.Element) -> bool:
+        """
+        Check if this visitor can handle the given node.
+
+        Args:
+            node: The MathML element to check
+
+        Returns:
+            True if node is an <mn> element, False otherwise
+        """
+        from ..utils import local_name as _local
+        return _local(node.tag) == 'mn'
+
+    @property
+    def element_name(self) -> str:
+        """Get the element name this visitor handles."""
+        return 'mn'
+
+    def __repr__(self) -> str:
+        """String representation for debugging."""
+        return f"MnVisitor(strategy={self.strategy.name})"