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/visitor_registry.py

@@ -0,0 +1,148 @@
+"""
+Visitor registry/factory for MathML element visitors.
+
+This module provides a centralized registry for mapping MathML element
+names to their corresponding visitor classes.
+"""
+
+from typing import Dict, Type, Optional, List
+from ..core.interfaces import Visitor, Strategy, VisitorRegistry as IVisitorRegistry
+from ..core.context import ConversionContext
+
+
+class VisitorRegistry(IVisitorRegistry):
+    """
+    Registry for MathML element visitors.
+
+    This class maintains a mapping of element names (e.g., 'mi', 'mo', 'mn')
+    to their corresponding visitor classes. It provides visitor instances
+    on demand with the appropriate strategy and context injected.
+
+    Example:
+        >>> registry = VisitorRegistry()
+        >>> registry.register('mi', MiVisitor)
+        >>> registry.register('mo', MoVisitor)
+        >>> strategy = MathStrategy()
+        >>> context = ConversionContext(input_type='mathml')
+        >>> mi_visitor = registry.get_visitor('mi', strategy, context)
+    """
+
+    def __init__(self, context: Optional[ConversionContext] = None):
+        """
+        Initialize the registry with empty mappings.
+
+        Args:
+            context: Optional shared conversion context for all visitors
+        """
+        self._visitors: Dict[str, Type[Visitor]] = {}
+        self._default_visitor: Type[Visitor] | None = None
+        self.context = context
+
+    def register(self, element_name: str, visitor_class: type) -> None:
+        """
+        Register a visitor class for a specific element type.
+
+        Args:
+            element_name: MathML element name (e.g., 'mi', 'mo', 'mn')
+            visitor_class: The visitor class to handle this element
+
+        Raises:
+            TypeError: If visitor_class is not a subclass of Visitor
+        """
+        if not issubclass(visitor_class, Visitor):
+            raise TypeError(
+                f"visitor_class must be a subclass of Visitor, "
+                f"got {type(visitor_class)}"
+            )
+
+        self._visitors[element_name] = visitor_class
+
+    def get_visitor(self, element_name: str, strategy: Strategy, context: Optional[ConversionContext] = None) -> Visitor:
+        """
+        Get a visitor instance for the given element type.
+
+        Args:
+            element_name: MathML element name (e.g., 'mi', 'mo')
+            strategy: The conversion strategy to inject into the visitor
+            context: Optional conversion context (uses registry's context if not provided)
+
+        Returns:
+            Visitor instance configured with the strategy and context
+
+        Raises:
+            ValueError: If no visitor registered for element_name and no default set
+        """
+        visitor_class = self._visitors.get(element_name)
+
+        if visitor_class is None:
+            if self._default_visitor is not None:
+                visitor_class = self._default_visitor
+            else:
+                raise ValueError(
+                    f"No visitor registered for element '{element_name}' "
+                    f"and no default visitor configured"
+                )
+
+        # Use provided context or fall back to registry's context
+        ctx = context if context is not None else self.context
+
+        # Try to instantiate with context, fall back to strategy-only if needed
+        try:
+            return visitor_class(strategy, ctx)
+        except TypeError:
+            # Visitor doesn't accept context parameter yet
+            return visitor_class(strategy)
+
+    def has_visitor(self, element_name: str) -> bool:
+        """
+        Check if a visitor is registered for the element type.
+
+        Args:
+            element_name: MathML element name
+
+        Returns:
+            True if visitor is registered or default exists, False otherwise
+        """
+        return element_name in self._visitors or self._default_visitor is not None
+
+    def set_default_visitor(self, visitor_class: Type[Visitor]) -> None:
+        """
+        Set a default visitor for unregistered element types.
+
+        Args:
+            visitor_class: The visitor class to use as default
+
+        Raises:
+            TypeError: If visitor_class is not a subclass of Visitor
+        """
+        if not issubclass(visitor_class, Visitor):
+            raise TypeError(
+                f"visitor_class must be a subclass of Visitor, "
+                f"got {type(visitor_class)}"
+            )
+
+        self._default_visitor = visitor_class
+
+    def get_registered_elements(self) -> List[str]:
+        """
+        Get list of all registered element names.
+
+        Returns:
+            List of element names with registered visitors
+        """
+        return list(self._visitors.keys())
+
+    def clear(self) -> None:
+        """Clear all registered visitors."""
+        self._visitors.clear()
+        self._default_visitor = None
+
+    def __repr__(self) -> str:
+        """String representation for debugging."""
+        elements = ', '.join(self._visitors.keys()) if self._visitors else 'none'
+        default = f", default={self._default_visitor.__name__}" if self._default_visitor else ""
+        return f"VisitorRegistry(registered=[{elements}]{default})"
+
+    def __len__(self) -> int:
+        """Get number of registered visitors."""
+        return len(self._visitors)