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/maligngroup_visitor.py

@@ -0,0 +1,88 @@
+r"""
+Visitor for <maligngroup> (alignment group marker) MathML elements.
+
+The <maligngroup/> element is an empty element used within table cells (<mtd>)
+to mark alignment groups. It's used to control horizontal alignment across
+table columns for complex multi-line expressions.
+
+In LaTeX conversion, alignment groups are handled implicitly by the array/matrix
+environment's column specifications (e.g., {lll} for left-aligned columns).
+Therefore, maligngroup markers are treated as transparent (no output).
+"""
+
+from lxml import etree as ET
+from ..core.interfaces import Visitor, Strategy
+from ..utils import local_name as _local
+
+
+class MaligngroupVisitor(Visitor):
+    r"""
+    Handles <maligngroup/> (alignment group marker) MathML elements.
+
+    Treats maligngroup as an invisible marker since LaTeX handles alignment
+    through column specifications in array/matrix environments. The element
+    is completely ignored in conversion.
+
+    Examples:
+        Alignment group in cell:
+            <mtd>
+                <maligngroup/>
+                <mi>x</mi>
+            </mtd>
+            → x (maligngroup ignored)
+
+        Multiple alignment groups:
+            <mtd>
+                <maligngroup groupalign="left"/>
+                <mi>a</mi>
+                <maligngroup groupalign="right"/>
+                <mi>b</mi>
+            </mtd>
+            → a b (both maligngroup markers ignored)
+
+        Group with alignment attribute:
+            <maligngroup groupalign="center"/>
+            → (empty - no output)
+
+    Note:
+        LaTeX doesn't support MathML's alignment group concept. Alignment
+        is controlled by column specifications in the array/matrix preamble
+        (e.g., {ccc} for center-aligned, {lll} for left-aligned).
+        Therefore, maligngroup elements produce no output.
+    """
+
+    def __init__(self, strategy: Strategy):
+        """Initialize the Maligngroup visitor."""
+        super().__init__(strategy)
+
+    def visit(self, node: ET.Element) -> str:
+        r"""
+        Convert <maligngroup/> element (returns empty string).
+
+        Args:
+            node: The <maligngroup/> element to convert
+
+        Returns:
+            Empty string (maligngroup is invisible in LaTeX)
+
+        Raises:
+            ValueError: If node is not a <maligngroup/> element
+        """
+        if not self.can_handle(node):
+            raise ValueError(f"MaligngroupVisitor cannot handle element '{node.tag}'")
+
+        # Maligngroup is an invisible alignment marker - no output
+        return ""
+
+    def can_handle(self, node: ET.Element) -> bool:
+        """Check if this visitor can handle the given node."""
+        return _local(node.tag) == 'maligngroup'
+
+    @property
+    def element_name(self) -> str:
+        """Get the element name this visitor handles."""
+        return 'maligngroup'
+
+    def __repr__(self) -> str:
+        """String representation for debugging."""
+        return f"MaligngroupVisitor(strategy={self.strategy.name})"