feat: support git repositories and project management

- Git (JGit) log fetching: mirror clone cache, incremental fetch, time/author filter, HTTPS token & SSH key auth
- Git preset management and /api/git/* endpoints (test-connection, version-range, fetch)
- Markdown report generalization: project meta, commit range, short hash entries
- Project management: project entities, drag-drop repo assignment, sorting, rename sync, non-empty delete protection
- AI analysis: project-based grouping merges SVN+Git commits, excludes empty projects from Excel
- Batch fetch: skip repos without logs instead of aborting the whole flow
- Frontend: project management page, repo page project dropdown, Git fields, sidebar updates
- Tests: GitLogFetcherTest, DateRangeResolverTest, ProjectConfigServiceTest, merge/exclusion coverage

pom.xml

@@ -33,6 +33,18 @@
             <version>1.10.11</version>
         </dependency>
 
+        <!-- JGit for Git operations (5.13.x 是兼容 Java 8 的最后一个版本线) -->
+        <dependency>
+            <groupId>org.eclipse.jgit</groupId>
+            <artifactId>org.eclipse.jgit</artifactId>
+            <version>5.13.3.202401111512-r</version>
+        </dependency>
+        <dependency>
+            <groupId>org.eclipse.jgit</groupId>
+            <artifactId>org.eclipse.jgit.ssh.apache</artifactId>
+            <version>5.13.3.202401111512-r</version>
+        </dependency>
+
         <!-- Apache POI for Excel operations -->
         <dependency>
             <groupId>org.apache.poi</groupId>