feat: add FetchUrlTool with proxy support and cross-OS path sanitization

- Implement native FetchUrlTool using reqwest for HTTP fetching, which respects HTTP_PROXY, HTTPS_PROXY, and NO_PROXY natively.
- Introduce sanitize_path in utils to bidirectionally handle Windows/WSL path mapping, applying it to various search/git handlers.
- Update .gitignore to exclude mcp_store.redb and tantivy_index.

server/src/handlers/meta.rs

@@ -331,6 +331,10 @@ impl McpTool for QueryRecentChangesHandler {
                 .skip(offset)
                 .take(limit)
                 .cloned()
+                .map(|mut c| {
+                    c.file_path = crate::handlers::utils::sanitize_path(&c.file_path);
+                    c
+                })
                 .collect();
             Ok::<String, crate::error::AppError>(serde_yaml::to_string(&filtered)?)
         })?;