fix(git): prefer connections.proxy over legacy flat keys

Keep git proxy lookup aligned with layered config, with proxy_* fallback.

mytoolkit/commands/git.py

@@ -11,12 +11,22 @@ from mytoolkit.config import config
 
 
 def _get_proxies() -> dict[str, str]:
-    """Get git proxies from config."""
-    proxies = {}
+    """Get git proxies from config.
+
+    Prefers hierarchical ``connections.proxy.<name>``; falls back to legacy
+    flat ``proxy_<name>`` keys for older configs.
+    """
+    proxies: dict[str, str] = {}
+    nested = config.get("connections.proxy")
+    if isinstance(nested, dict):
+        for name, value in nested.items():
+            if isinstance(value, str) and value:
+                proxies[str(name)] = value
+    if proxies:
+        return proxies
     for key, value in config.get_all().items():
-        if key.startswith("proxy_"):
-            name = key[6:]  # Remove 'proxy_' prefix
-            proxies[name] = value
+        if key.startswith("proxy_") and isinstance(value, str) and value:
+            proxies[key[6:]] = value
     return proxies