feat: bump KubeSolo to v1.1.5 + cross-arch CI workflow

Phase 4 of v0.3 — KubeSolo version bump and CI gating.

KubeSolo v1.1.0 → v1.1.5 brings:
- New flag --disable-ipv6 (v1.1.5)
- New flag --db-wal-repair (v1.1.5) — important for power-loss resilience
  on edge appliances; surfaced as kubesolo.db-wal-repair in cloud-init
- New flag --full (v1.1.4) — disables edge-optimised k8s overrides
- Pod egress connectivity fix after reboot (v1.1.4)
- Registry config persistence fix (v1.1.5)
- k8s 1.34.7, CoreDNS 1.14.3, Go 1.26.2

All three new flags wired into cloud-init: config.go fields, kubesolo.go
extra-flag emission, full-config.yaml example.

Supply-chain hygiene:
- Per-arch checksums: KUBESOLO_SHA256_AMD64 and KUBESOLO_SHA256_ARM64 in
  versions.env. Replaces the single shared KUBESOLO_SHA256 that couldn't
  meaningfully verify both binaries at once.
- Checksum now applied to the tarball (the immutable upstream artifact)
  rather than the post-extract binary.

CI:
- New .gitea/workflows/build-arm64.yaml routes the full kernel + rootfs +
  disk-image build to the Odroid arm64-linux runner. Triggers on push to
  main, tags, and manual workflow_dispatch. The boot smoke test is
  continue-on-error because KubeSolo's first-boot image import deadline
  fires under QEMU TCG on the Odroid.

VERSION bumped to 0.3.0-dev. CHANGELOG entry under [0.3.0-dev] captures all
Phase 1-4 work + the known limitations documented in arm64-status.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

build/config/versions.env

@@ -11,8 +11,11 @@ TINYCORE_ISO_URL=${TINYCORE_MIRROR}/${TINYCORE_VERSION%%.*}.x/${TINYCORE_ARCH}/r
 # KubeSolo
 # Pinned release tag from https://github.com/portainer/kubesolo/releases.
 # Bump here and re-run `make fetch` to pull a new version.
-KUBESOLO_VERSION=v1.1.0
+KUBESOLO_VERSION=v1.1.5
 KUBESOLO_INSTALL_URL=https://get.kubesolo.io
+# Per-arch SHA256 of the musl tarball (verified at fetch time when non-empty).
+KUBESOLO_SHA256_AMD64=565bd5fd98fc8ce09160e646b55de3493c782d74c0e0c46ccf130ff4bcabab81
+KUBESOLO_SHA256_ARM64=db865a5e9b2617d595f9c2b7d011272edc94587621a9690e2de0f47cc94f0748
 
 # Build tools (used inside builder container)
 GRUB_VERSION=2.12
@@ -22,7 +25,6 @@ SYSLINUX_VERSION=6.03
 # Populate by running: sha256sum build/cache/<file>
 # Leave empty to skip verification (useful for first fetch)
 TINYCORE_ISO_SHA256=""
-KUBESOLO_SHA256=""
 NETFILTER_TCZ_SHA256=""
 NET_BRIDGING_TCZ_SHA256=""
 IPTABLES_TCZ_SHA256=""