build: migrate from Dapper to single-Dockerfile build system

[bk201]

Problem:

Replace the Dapper-driven build (Dockerfile.dapper + scripts/entry/ci/ default/release) with a single Dockerfile whose stages are driven directly by make <target> via docker build --target.

Solution:

• Dockerfile: add builder, base, build, validate, validate-ci, test, generate, and generate-manifest stages (with scratch output stages where files need to be extracted to the host)
• Makefile: rewrite around DOCKER_BUILD, MK_REPO_ID-scoped BuildKit caches, and a gen-version-env prerequisite on every docker build target
• scripts/version: add .git availability guard with .version_env fallback so container builds work without a .git directory; replace go env GOHOSTARCH with uname -m for host-side use; write .version_env after each normal (non-CI) invocation
• .dockerignore: exclude .git to keep the build context lean
• .gitignore: exclude the generated scripts/.version_env artifact

Deleted: Dockerfile.dapper, scripts/ci, scripts/default, scripts/entry, scripts/release (all replaced by Makefile targets).

Related Issue:
harvester/harvester#10608

Test plan:

make should works

[Copilot]

Pull request overview

This PR replaces the previous Dapper-driven build/CI entrypoint scripts with a single multi-stage Dockerfile and a Makefile that drives builds via docker build --target ..., while adding a .version_env fallback to support container builds where .git is excluded from the Docker context.

Changes:

• Added a new multi-stage Dockerfile with dedicated stages for build/validate/test/generate outputs and local extraction via --output type=local.
• Rewrote the Makefile to orchestrate the new Docker build targets, BuildKit caches, and a gen-version-env prerequisite.
• Updated version/package scripts and ignore files to support .git-less container builds and track the generated scripts/.version_env.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
scripts/version	Adds .git-availability guard and .version_env fallback; updates arch detection and writes a generated env file.
scripts/package	Ensures packaging scripts run from the scripts directory for consistent relative-path behavior.
Makefile	Replaces Dapper invocation with docker build --target workflow, BuildKit cache IDs, and new build targets.
Dockerfile	Introduces multi-stage build system with cache mounts and output stages for artifacts extraction.
.gitignore	Ignores generated scripts/.version_env.
.dockerignore	Excludes .git (and adds a few editor/temp patterns) to reduce build context size.
Dockerfile.dapper	Removed (superseded by new Dockerfile + Makefile targets).
scripts/release	Removed (superseded by Makefile targets).
scripts/entry	Removed (no longer needed without Dapper entrypoint pattern).
scripts/default	Removed (superseded by Makefile targets).
scripts/ci	Removed (superseded by Makefile targets).

Comments suppressed due to low confidence (1)

scripts/version:45

• if [[ -n ${BUILD_FOR_CI} ]]; then ... return ... isn’t a reliable early-exit when scripts/version is executed (e.g., make gen-version-env) because return fails outside of a sourced context and the script continues. When fixing this (return vs exit), ensure CI still generates scripts/.version_env before Docker builds (since .git is excluded from the build context and container stages may rely on the fallback).

if [[ -n ${BUILD_FOR_CI} ]]; then
    TAG=${COMMIT}
    return 0 2>/dev/null || true
fi

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[bk201]

@tserong can you review and take over the PR? I've done my best, but there may still be some missing pieces.

[tserong]

Sure @bk201, will do.