Fix testcontainers leak: label containers and clean up orphans

Testcontainers postgres instances were never cleaned up on process exit
(OnceLock statics don't run destructors) or abnormal termination,
accumulating 115+ orphaned containers and 4.77 GB of volumes.

- Label test containers with com.betweenrows.test for identification
- Clean up orphaned labeled containers in pre-commit hook before tests
- Store ContainerAsync in SharedPostgres struct instead of holding via
  pending future

Author: jumpbetweenrows

.githooks/pre-commit

@@ -1,6 +1,13 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
+# Clean up orphaned test containers from previous interrupted runs
+orphans=$(docker ps -q --filter "label=com.betweenrows.test" 2>/dev/null || true)
+if [ -n "$orphans" ]; then
+    echo "→ cleaning up orphaned test containers"
+    docker rm -f $orphans >/dev/null 2>&1 || true
+fi
+
 echo "→ cargo fmt --check"
 cargo fmt --check
 

proxy/tests/support/mod.rs

@@ -65,6 +65,9 @@ pub struct SharedPostgres {
     pub url: String,
     pub host: String,
     pub port: u16,
+    /// Keeps the container alive. Dropped on normal process exit → container stops.
+    /// For abnormal exits (SIGKILL), the container label lets us find and clean orphans.
+    _container: testcontainers::ContainerAsync<testcontainers_modules::postgres::Postgres>,
 }
 
 static SHARED_PG: OnceLock<Option<SharedPostgres>> = OnceLock::new();
@@ -87,10 +90,15 @@ pub fn shared_postgres() -> Option<&'static SharedPostgres> {
                     }
                 };
                 rt.block_on(async {
+                    use testcontainers::core::ImageExt;
                     use testcontainers::runners::AsyncRunner;
                     use testcontainers_modules::postgres::Postgres;
 
-                    let container = match Postgres::default().start().await {
+                    let container = match Postgres::default()
+                        .with_label("com.betweenrows.test", "true")
+                        .start()
+                        .await
+                    {
                         Ok(c) => c,
                         Err(e) => {
                             eprintln!("testcontainers: could not start Postgres: {e}");
@@ -110,8 +118,9 @@ pub fn shared_postgres() -> Option<&'static SharedPostgres> {
                         url: format!("postgres://postgres:postgres@127.0.0.1:{port}/postgres"),
                         host: "127.0.0.1".to_string(),
                         port,
+                        _container: container,
                     }));
-                    // Keep container alive until the test process exits.
+                    // Keep the runtime alive so the container's async drop works on process exit.
                     std::future::pending::<()>().await;
                 });
             });