Update miniflux to main image tag, disable OTEL metrics in Dagger module

Point miniflux kustomization at the main-built v2.2.19-138e23d image
(replacing the branch tag). Disable the OTLP metrics exporter at module
import time to prevent ~11s retry delays in CI — the env var must be set
inside the module, not the runner shell, because the SDK runs inside the
Dagger engine container.

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

argocd/manifests/miniflux/kustomization.yaml

@@ -10,4 +10,4 @@ resources:
 
 images:
   - name: registry.ops.eblu.me/blumeops/miniflux
-    newTag: v2.2.19-e08c95c
+    newTag: v2.2.19-138e23d

src/blumeops/main.py

@@ -1,5 +1,10 @@
+import os
 from pathlib import Path
 
+# Disable OTLP metrics exporter before the Dagger SDK initializes OpenTelemetry.
+# The Dagger engine's local OTLP endpoint returns 500s, causing ~11s retry delays.
+os.environ.setdefault("OTEL_METRICS_EXPORTER", "none")
+
 import dagger
 from dagger import dag, function, object_type