chore(devops): dotnet release image + compose/bootstrap stabilization

Sprint SPRINT_20260417_024_DevOps_dotnet_release_image_stabilization.

- Dockerfile.platform + Dockerfile.dotnet-service adjustments for
  deterministic layer ordering and cache-friendly publish.
- devops/release/components.json updates.
- devops/compose: .env, README, legacy + stella-services docker-compose,
  stellaops env example, postgres-init 04/04b/15/16 authority + release
  schemas, setup.bootstrap.local.yaml.
- Gitea build_release.py script.
- scripts/register-local-integrations.ps1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

devops/compose/postgres-init/15-platform-context-and-releases.sql

@@ -70,19 +70,5 @@ CREATE INDEX IF NOT EXISTS idx_control_bundles_tenant_name
 CREATE INDEX IF NOT EXISTS idx_control_bundles_tenant_updated
     ON release.control_bundles (tenant_id, updated_at DESC, id);
 
--- Seed demo context data for local development
-INSERT INTO platform.context_regions (region_id, display_name, sort_order, enabled)
-VALUES
-    ('us-east', 'US East', 1, true),
-    ('us-west', 'US West', 2, true),
-    ('eu-west', 'EU West', 3, true)
-ON CONFLICT (region_id) DO NOTHING;
-
-INSERT INTO platform.context_environments (environment_id, region_id, environment_type, display_name, sort_order, enabled)
-VALUES
-    ('dev', 'us-east', 'development', 'Development', 1, true),
-    ('stage', 'us-east', 'staging', 'Staging', 2, true),
-    ('prod-us-east', 'us-east', 'production', 'Production US East', 3, true),
-    ('prod-us-west', 'us-west', 'production', 'Production US West', 4, true),
-    ('prod-eu-west', 'eu-west', 'production', 'Production EU West', 5, true)
-ON CONFLICT (environment_id) DO NOTHING;
+-- Context regions/environments are intentionally left empty on fresh installs.
+-- The setup and admin surfaces create truthful operator-owned state as needed.