feat(git): add proxy run command with auto-unset on exit

Add `git proxy run <name>` that sets proxy, runs the associated
command, and auto-restores/unsets proxy on exit or Ctrl-C.
Also fix click.Exit usage for Click 8.x compatibility.

bin/commands/git.py

@@ -1,6 +1,9 @@
 """Git utilities including proxy management."""
 
+import shutil
+import signal
 import subprocess
+import sys
 
 import click
 
@@ -64,7 +67,7 @@ def proxy_set(name: str) -> None:
     if name not in proxies:
         click.echo(f"Unknown proxy: {name}", err=True)
         click.echo(f"Available: {', '.join(proxies.keys())}", err=True)
-        raise click.Exit(1)
+        sys.exit(1)
 
     proxy_url = proxies[name]
     subprocess.run(
@@ -114,3 +117,88 @@ def proxy_list_cmd() -> None:
     click.secho("Available proxies:", fg="cyan")
     for name, url in proxies.items():
         click.echo(f"  {name:12} {url}")
+
+
+@proxy_cmd.command("run")
+@click.argument("name", shell_complete=_complete_proxy_names)
+@click.argument("command", nargs=-1, required=False)
+def proxy_run(name: str, command: tuple[str, ...]) -> None:
+    """Set proxy, run a command, auto-unset on exit.
+
+    If no COMMAND is given, tries to run a program with the same name as the proxy.
+    If that program is not found, sets the proxy and waits for Ctrl-C.
+    """
+    proxies = _get_proxies()
+    if name not in proxies:
+        click.echo(f"Unknown proxy: {name}", err=True)
+        click.echo(f"Available: {', '.join(proxies.keys())}", err=True)
+        sys.exit(1)
+
+    # Save current state
+    old_http = _get_git_proxy("http.proxy")
+    old_https = _get_git_proxy("https.proxy")
+
+    proxy_url = proxies[name]
+    subprocess.run(
+        ["git", "config", "--global", "http.proxy", proxy_url], check=True
+    )
+    subprocess.run(
+        ["git", "config", "--global", "https.proxy", proxy_url], check=True
+    )
+    click.secho(f"Git proxy set to {name}: {proxy_url}", fg="green")
+
+    # Determine what to run
+    cmd_to_run = list(command) if command else None
+    if cmd_to_run is None:
+        if shutil.which(name):
+            cmd_to_run = [name]
+
+    def cleanup():
+        if old_http == "(not set)":
+            _unset_git_proxy("http.proxy")
+        else:
+            subprocess.run(
+                ["git", "config", "--global", "http.proxy", old_http],
+                capture_output=True,
+                check=False,
+            )
+        if old_https == "(not set)":
+            _unset_git_proxy("https.proxy")
+        else:
+            subprocess.run(
+                ["git", "config", "--global", "https.proxy", old_https],
+                capture_output=True,
+                check=False,
+            )
+        click.secho("Git proxy restored", fg="green")
+
+    if cmd_to_run:
+        click.secho(f"Running: {' '.join(cmd_to_run)}", fg="cyan")
+        click.secho("Press Ctrl-C to stop and auto-unset proxy\n", fg="cyan")
+        proc = None
+        try:
+            proc = subprocess.Popen(cmd_to_run)
+            proc.wait()
+        except KeyboardInterrupt:
+            if proc is not None:
+                proc.send_signal(signal.SIGINT)
+                try:
+                    proc.wait(timeout=5)
+                except subprocess.TimeoutExpired:
+                    proc.terminate()
+                    proc.wait()
+        finally:
+            cleanup()
+        if proc is not None:
+            sys.exit(proc.returncode)
+        sys.exit(0)
+    else:
+        click.secho(
+            f"Proxy active. Press Ctrl-C to stop and auto-unset proxy", fg="cyan"
+        )
+        try:
+            signal.pause()
+        except KeyboardInterrupt:
+            pass
+        finally:
+            cleanup()