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/Cargo.toml

@@ -14,7 +14,7 @@ clap = { version = "4.6.6", features = ["derive"] }
 dirs = "7.0.0"
 futures-util = "0.3.34"
 redb = "4.3.0"
-reqwest = { version = "0.13", default-features = false, features = ["stream", "json"] }
+reqwest = { version = "0.13", default-features = false, features = ["stream", "json", "rustls"] }
 schemars = "1.2.2"
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.151"