Fix CI healthcheck endpoint and bundled install FK violations

Two bugs preventing the test-runners CI job from passing:

1. Health check used GET /api/v1/auth/login — a POST-only route that
   always returns 404. Changed to GET /api/v1/health which exists.

2. Bundled package install passed empty strings to FK-constrained
   columns (global_settings.updated_by, workflows.created_by),
   causing FOREIGN KEY constraint failures on every surface and
   workflow package. Fixed by resolving the bootstrap admin user ID
   at startup and threading it through the install path.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.ci.yml

@@ -18,7 +18,7 @@
 services:
   armature:
     healthcheck:
-      test: ["CMD", "curl", "-sf", "http://localhost:80/api/v1/auth/login"]
+      test: ["CMD", "curl", "-sf", "http://localhost:80/api/v1/health"]
       interval: 2s
       timeout: 3s
       retries: 30