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/mtr_visitor.py

@@ -0,0 +1,98 @@
+r"""
+Visitor for <mtr> (table row) MathML elements.
+
+The <mtr> element represents a row in a table/matrix. It is a helper element
+that contains <mtd> (table cell) children.
+
+This visitor is primarily used by MtableVisitor to convert table rows.
+"""
+
+from lxml import etree as ET
+from ..core.interfaces import Visitor, Strategy
+from ..utils import local_name as _local
+
+
+class MtrVisitor(Visitor):
+    r"""
+    Handles <mtr> (table row) MathML elements.
+
+    Converts table rows to LaTeX format with cells separated by & and
+    terminated with \\.
+
+    Examples:
+        Simple row:
+            <mtr><mtd><mn>1</mn></mtd><mtd><mn>2</mn></mtd></mtr>
+            → 1 & 2 \\
+
+        Row with expressions:
+            <mtr><mtd><mi>x</mi></mtd><mtd><mi>y</mi></mtd></mtr>
+            → x & y \\
+
+        Single cell row:
+            <mtr><mtd><mi>a</mi></mtd></mtr>
+            → a \\
+
+        Empty row:
+            <mtr></mtr>
+            → \\
+    """
+
+    def __init__(self, strategy: Strategy):
+        """Initialize the Mtr visitor."""
+        super().__init__(strategy)
+
+    def visit(self, node: ET.Element) -> str:
+        r"""
+        Convert <mtr> element to LaTeX row.
+
+        Args:
+            node: The <mtr> element to convert
+
+        Returns:
+            LaTeX string with cells separated by & and terminated with \\
+
+        Raises:
+            ValueError: If node is not an <mtr> element
+        """
+        if not self.can_handle(node):
+            raise ValueError(f"MtrVisitor cannot handle element '{node.tag}'")
+
+        # Convert all <mtd> children to cells
+        cells = []
+        for child in node:
+            if _local(child.tag) == "mtd":
+                cell_latex = self._convert_cell(child)
+                cells.append(cell_latex)
+
+        # Join cells with & and add row terminator
+        if not cells:
+            return "\\\\"
+
+        return " & ".join(cells) + " \\\\"
+
+    def _convert_cell(self, node: ET.Element) -> str:
+        """
+        Convert a single <mtd> (table cell) element.
+
+        Args:
+            node: The <mtd> element
+
+        Returns:
+            LaTeX string for cell content
+        """
+        # Use MtdVisitor for proper cell conversion
+        from .mtd_visitor import MtdVisitor
+        return MtdVisitor(self.strategy).visit(node)
+
+    def can_handle(self, node: ET.Element) -> bool:
+        """Check if this visitor can handle the given node."""
+        return _local(node.tag) == 'mtr'
+
+    @property
+    def element_name(self) -> str:
+        """Get the element name this visitor handles."""
+        return 'mtr'
+
+    def __repr__(self) -> str:
+        """String representation for debugging."""
+        return f"MtrVisitor(strategy={self.strategy.name})"