Raise TimeoutError in wait_until_healthy() on timeout

Replace silent string return with TimeoutError that includes container
name, elapsed time, and logs. Deployment now fails fast with a clear
root cause instead of cascading silently into downstream failures.

Closes #52

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: szachovy

CHANGELOG.md

@@ -16,6 +16,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * CI workflow to build and push service images to GitHub Container Registry on master merge. (#97)
 * Pull-first with local build fallback for container images during deployment. (#97)
 
+### Fixed
+
+* wait_until_healthy() raises TimeoutError instead of returning a string on timeout. (#52)
+
 ### Changed
 
 * Completed [ARCHITECTURE.md](./docs/ARCHITECTURE.md) (#93)

src/container.py

@@ -205,7 +205,10 @@ def wait_until_healthy(self, cls: typing.Type[ContainerInstance]) -> str:
                 if self.client.containers.get(self.container).attrs["State"]["Health"]["Status"] == "healthy":
                     return f"{self.get_logs()}\nContainer {self.container} is healthy"
             time.sleep(cls.healthcheck_interval)
-        return f"{self.get_logs()}\nTimeout while waiting for {self.container} healthcheck to be healthy"
+        elapsed = cls.healthcheck_start_period + cls.healthcheck_retries * cls.healthcheck_interval
+        raise TimeoutError(
+            f"{self.get_logs()}\nContainer {self.container} not healthy after {elapsed}s"
+        )
 
     def run_mysql_server(self) -> None:
         class MySQLServer(ContainerInstance):