Initial implementation: aptly container image, Compose stacks, Helm chart, and Gitea Actions pipelines

Provides a self-contained, containerized aptly (Debian repo manager)
stack with independently releasable image and Helm chart versions.

- images/: aptly-server (aptly built from source, cross-compiled) and
  aptly-deb-builder (nfpm + dpkg-buildpackage) container images
- rootfs/: shared aptly-init/aptly-reconcile/aptly-push/aptly-pack
  scripts consumed identically by Compose and the Helm chart, driven
  by one declarative state.yaml contract
- compose/: test (ephemeral, open) and production docker-compose
  stacks with an nginx read/auth sidecar
- charts/aptly/: aptly-native Helm chart covering every security
  posture from fully open to authenticated read+write, Ingress and
  Gateway API support (usable in parallel for migration scenarios),
  metrics, and declarative repo/mirror/publish reconciliation via a
  Helm hook
- .gitea/workflows/: CI (lint, template, kubeconform, E2E smoke test)
  plus separately tagged image (image/v*) and chart (chart/v*)
  releases, weekly rebuilds, and a preflight workflow validating the
  runner's Docker/Helm-OCI capabilities
- pubkeys/: RSA chart-signing key for Helm --sign / Artifact Hub's
  signKey annotation (Helm can't verify Ed25519 keys)
- docs/, README.md, charts/aptly/README.md: usage, security, and
  versioning documentation

charts/aptly/Chart.yaml

@@ -0,0 +1,33 @@
+apiVersion: v2
+name: aptly
+description: >-
+  aptly (Debian repository management tool) on Kubernetes — a StatefulSet with
+  an nginx read/auth sidecar, a fully aptly-native values API, and declarative
+  repo/mirror/publish state reconciled via a Helm hook.
+type: application
+version: 0.1.0
+appVersion: "1.6.3-1"
+home: https://git.morlana.online/f.weber/aptly-containerized
+sources:
+  - https://git.morlana.online/f.weber/aptly-containerized
+  - https://github.com/aptly-dev/aptly
+keywords:
+  - aptly
+  - apt
+  - debian
+  - package-repository
+  - artifact-repository
+maintainers:
+  - name: Florian Weber
+    email: f.weber@flweber.me
+icon: https://www.aptly.info/img/aptly_medium.png
+annotations:
+  artifacthub.io/license: MIT
+  artifacthub.io/links: |
+    - name: aptly upstream
+      url: https://www.aptly.info/
+    - name: Source
+      url: https://git.morlana.online/f.weber/aptly-containerized
+  artifacthub.io/signKey: |
+    fingerprint: FC35C0FAA26605C4C21C7BBFBF43884145E5AA94
+    url: https://git.morlana.online/f.weber/aptly-containerized/raw/branch/main/pubkeys/chart-signing.asc