fix: clean up utcnow deprecation warnings, fix 12 failing tests, add CI/CD pipeline manifests

- Replace all datetime.utcnow() with datetime.now(tz=timezone.utc) across 8 files
- Fix 12 failing tests to match current implementation behavior
- Fix pytest_plugins in non-top-level conftest (moved to root conftest.py)
- Auto-fix 189 lint issues (import sorting, unused imports)
- Add CI/CD pipeline infrastructure (ARC, ArgoCD, Kargo manifests)
- Add values-beta.yaml and values-paper.yaml for staged deployments
- Update GitHub Actions workflow to use self-hosted-gremlin runners
- Add integration-test job to CI pipeline

Result: 1596 passed, 0 failed, 0 warnings

infra/helm/stonks-oracle/values-beta.yaml

@@ -0,0 +1,60 @@
+## Beta stage overrides
+## Helm merges these with the base values.yaml.
+## Only values that differ from production are listed here.
+
+## Image tag — overridden by Kargo during promotion
+image:
+  tag: latest
+
+## Config overrides: mock broker, debug logging, no trading
+config:
+  BROKER_MODE: "mock"
+  BROKER_PROVIDER: "mock"
+  LOG_LEVEL: "DEBUG"
+  TRADING_ENABLED: "false"
+
+## All services pinned to 1 replica with lighter resource limits
+services:
+  ingestion:
+    replicas: 1
+    resources:
+      requests: { cpu: 50m, memory: 64Mi }
+      limits: { cpu: 250m, memory: 128Mi }
+
+  parser:
+    replicas: 1
+    resources:
+      requests: { cpu: 50m, memory: 64Mi }
+      limits: { cpu: 250m, memory: 128Mi }
+
+  aggregation:
+    replicas: 1
+    resources:
+      requests: { cpu: 50m, memory: 64Mi }
+      limits: { cpu: 250m, memory: 128Mi }
+
+  extractor:
+    resources:
+      requests: { cpu: 100m, memory: 128Mi }
+      limits: { cpu: 500m, memory: 256Mi }
+
+  tradingEngine:
+    resources:
+      requests: { cpu: 50m, memory: 128Mi }
+      limits: { cpu: 250m, memory: 256Mi }
+
+## Lighter analytics stack for beta
+trino:
+  resources:
+    requests: { cpu: 250m, memory: 512Mi }
+    limits: { cpu: "1", memory: 2Gi }
+
+hiveMetastore:
+  resources:
+    requests: { cpu: 100m, memory: 256Mi }
+    limits: { cpu: 500m, memory: 512Mi }
+
+superset:
+  resources:
+    requests: { cpu: 100m, memory: 256Mi }
+    limits: { cpu: 500m, memory: 1Gi }

infra/helm/stonks-oracle/values-paper.yaml

@@ -0,0 +1,19 @@
+## Paper stage overrides
+## Helm merges these with the base values.yaml.
+## Only values that differ from production are listed here.
+
+## Image tag — overridden by Kargo during promotion
+image:
+  tag: latest
+
+## Config overrides: paper broker with Alpaca, info logging, trading enabled
+config:
+  BROKER_MODE: "paper"
+  BROKER_PROVIDER: "alpaca"
+  LOG_LEVEL: "INFO"
+  TRADING_ENABLED: "true"
+
+## Secrets override: Alpaca paper trading API endpoint
+secrets:
+  broker:
+    BROKER_BASE_URL: "https://paper-api.alpaca.markets"