v0.5.0 source release: declarative package runtime This minor source milestone cuts the stable checkpoint for the declaration inversion: package.star exports a declaration while Sidecat owns validation, typed argv binding, execution, parsing, contract generation, dry-run strategy, and from-source package execution. It includes the current sidecat.cli, sidecat.parse, sidecat.vcs, and sidecat.container declaration kits, a thin declarative git package, a non-vcs docker proof, generated contract checks, linter findings, and real ProcessExecutor smoke coverage. This release is not recommended for use. It is not a production runtime, stable command surface, stable package API, official binary distribution, complete AAuth product, complete federation implementation, or complete Sidebar/Sidebird product. Known debt accepted for 0.5.0: sidecat package run and sidecat package lint still expose noun-grouped command shape. The 0.6.0 milestone is reserved for the bounded verb-object command language, JSON payload calls, validate-not-lint, git package refresh, git-workbench retirement decision, machine-readable call templates, and guardrails against Gen 2-style command sprawl.