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

containers/miniflux/container.py

@@ -0,0 +1,61 @@
+"""Miniflux RSS feed reader — native Dagger build.
+
+Two-stage build: Go (backend with PIE), Alpine (runtime).
+Source cloned from forge mirror.
+"""
+
+import dagger
+from dagger import dag
+
+from blumeops.containers import (
+    alpine_runtime,
+    clone_from_forge,
+    oci_labels,
+)
+
+VERSION = "2.2.19"
+
+
+async def build(src: dagger.Directory) -> dagger.Container:
+    source = clone_from_forge("miniflux", VERSION)
+
+    # Stage 1: Build Go backend (PIE mode, matching upstream Makefile)
+    ldflags = f"-s -w -X 'miniflux.app/v2/internal/version.Version={VERSION}'"
+    backend = (
+        dag.container()
+        .from_("golang:alpine3.22")
+        .with_exec(["apk", "add", "--no-cache", "build-base", "git"])
+        .with_directory("/app", source)
+        .with_workdir("/app")
+        .with_env_variable("CGO_ENABLED", "1")
+        .with_exec(
+            [
+                "go",
+                "build",
+                "-buildmode=pie",
+                f"-ldflags={ldflags}",
+                "-o",
+                "/miniflux",
+                ".",
+            ]
+        )
+    )
+
+    # Stage 2: Runtime (uses Alpine's built-in nobody:65534)
+    runtime = alpine_runtime(
+        extra_apk=["ca-certificates", "tzdata"],
+        create_user=False,
+    )
+    runtime = oci_labels(
+        runtime,
+        title="Miniflux",
+        description="Miniflux is a minimalist and opinionated feed reader",
+        version=VERSION,
+    )
+    return (
+        runtime.with_file("/usr/bin/miniflux", backend.file("/miniflux"))
+        .with_exposed_port(8080)
+        .with_env_variable("LISTEN_ADDR", "0.0.0.0:8080")
+        .with_user("65534")
+        .with_default_args(args=["/usr/bin/miniflux"])
+    )