Miniflux 2.2.19 + container.py migration + ty typechecker (#331)

## Summary

- Upgrade miniflux from 2.2.17 to 2.2.19 (security hardening, performance improvements)
- Migrate miniflux from Dockerfile to native Dagger container.py build
- Refactor `alpine_runtime()` helper to support existing users (nobody/65534)
- Add `ty` (Astral) Python typechecker to prek hooks

## Test plan

- [ ] `dagger call build --src=. --container-name=miniflux` succeeds
- [ ] `dagger call container-version --container-name=miniflux` returns 2.2.19
- [ ] `mise run container-version-check` passes
- [ ] `ty check` passes cleanly
- [ ] `prek run --all-files` passes
- [ ] CI builds container successfully
- [ ] Miniflux healthcheck passes after deploy from branch

Reviewed-on: #331

argocd/manifests/miniflux/kustomization.yaml

@@ -10,4 +10,4 @@ resources:
 
 images:
   - name: registry.ops.eblu.me/blumeops/miniflux
-    newTag: v2.2.17-613f05d
+    newTag: v2.2.19-e08c95c