#8217 chore: add local Go pipelines with Dagger

Summary

• Pin Dagger 1.0.0-beta.21 through mise and add a go-pipeline module with generated Go bindings.
• Expose local Go builds, lint, tests, and server/Functions/tunnel image workflows through dagger:go and dagger:go-test, reusing the existing mise tasks.
• Preserve test reports and exit status, support explicit build metadata and image architecture, and document local execution and caching.

Motivation

Provide reproducible, containerized Go workflows that developers can exercise locally before adopting Dagger in GitHub Actions. This establishes the local tooling first; workflow migration is deferred.

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Summary by cubic

Adds local Go build, lint, test, and runtime-image workflows through a mise-pinned Dagger pipeline; GitHub Actions integration remains deferred.

• dagger:go and dagger:go-test reuse existing scripts and are documented in .dagger/README.md.
• Docker-dependent builds run in a disposable in-container daemon, so no host socket or persistent daemon is needed.
• Build metadata and image architecture can be overridden, and test reports are exported without masking failures.
• Excludes generated Dagger files and dagger.lock from Cubic reviews.