fix(setup): install Docker 29.4.2 on Ubuntu 26.04 to fix failed setup

[pparage]

What

Ubuntu 26.04 (Plucky Puffin / resolute) installs fail because the provisioning script pins DOCKER_VERSION=28.5.0 and passes it to get.docker.com via --version. The resolute docker-ce repo has no 28.5.0, so the convenience script's apt-cache madison docker-ce | grep "$VERSION" finds nothing and exits:

INFO: Searching repository for VERSION '28.5.0'
ERROR: '28.5.0' not found amongst apt-cache madison results
sh: 214: docker: not found
Error: Failed to initialize Docker Swarm

Docker is never installed and setup aborts.

Root cause

Not missing upstream support (Docker's repo does support resolute) — it's a version-pin mismatch. The pinned 28.5.0 simply isn't in the resolute pool. Correctly diagnosed in #4501.

Fix

Repin the Docker version for Ubuntu 26.04 only, to a version present on every architecture Docker ships resolute for:

if [ "$OS_TYPE" = "ubuntu" ] && [ "$OS_VERSION" = "26.04" ]; then
	DOCKER_VERSION=29.4.2
fi

Why 29.4.2 and not the amd64 floor (29.3.1): the per-arch resolute pools don't agree. s390x is the binding architecture.

Arch	Available docker-ce in resolute pool
amd64 / arm64 / armhf	29.3.1 -> 29.5.3
s390x	29.4.0 -> 29.4.2 (no 29.3.1, no 29.5.x)
ppc64le	not shipped for resolute

29.3.1 would still fail on s390x; 29.5.x would fail on s390x too. 29.4.2 is the newest version common to all shipped arches, so a single pin works without SYS_ARCH gating. Verified against the live download.docker.com/.../dists/resolute/pool/stable/<arch>/ listings.

• Scoped to OS_TYPE=ubuntu + OS_VERSION=26.04; every other OS/release keeps 28.5.0 byte-for-byte.
• Detects via VERSION_ID (consistent with the rest of the script; codenames are never parsed).
• Placed after OS_VERSION is resolved and before the install banner, so the reported Docker version stays accurate and both the full-server and build-server paths are covered.
• POSIX sh-safe (verified with sh -n).

Note for maintainers

The standalone install.sh served from dokploy.com/install.sh (single-host bootstrap) carries the same DOCKER_VERSION=28.5.0 pin and will hit the identical failure. It lives outside this repo, so it needs the same override applied wherever that asset is built.

Fixes #4327, #4349. Closes #4501.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Pick a Docker pin that exists on s390x

On Ubuntu 26.04 s390x this pin still makes get.docker.com --version fail: Docker's Ubuntu docs list s390x as a supported architecture (https://docs.docker.com/engine/install/ubuntu/), but the official resolute s390x pool has docker-ce starting at 29.4.0 and no 29.3.1 (https://download.docker.com/linux/ubuntu/dists/resolute/pool/stable/s390x/). The convenience script searches apt-cache madison docker-ce | grep '$VERSION' and exits when no match is found, so gate this by SYS_ARCH or choose a version present for every supported 26.04 architecture.

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