git proxy: add start/stop/restart daemon lifecycle for FastGitHub.

Background daemons with port/PID tracking and Parallels socat, keep FastGithub logs off the TTY, and document install in the skill.

tests/test_git_proxy.py

@@ -0,0 +1,13 @@
+"""Unit tests for git proxy helpers."""
+
+from mytoolkit.commands.git import _proxy_loopback_port
+
+
+def test_proxy_loopback_port_http():
+    assert _proxy_loopback_port("http://127.0.0.1:38457") == 38457
+    assert _proxy_loopback_port("http://localhost:10080") == 10080
+
+
+def test_proxy_loopback_port_rejects_remote():
+    assert _proxy_loopback_port("http://10.211.55.2:38457") is None
+    assert _proxy_loopback_port("socks5://127.0.0.1:1080") is None