passdown v0.2.0

Added

• First-class Codex host support with a native .codex-plugin manifest and
  repo marketplace.
• Installer, skill-contract, version, and release-workflow regression suites.
• A single VERSION source of truth with manifest/tag agreement checks.
• Tag-gated GitHub Release automation.
• Executor environment preflight and setup guidance.

Changed

• Made intake, dispatch, and handoff configuration inherit root-to-nearest
  AGENTS.md values with nearest-key precedence.
• Made dispatch host-aware: Codex is an external executor only from another
  host, while native subagents use the portable subagent name.
• Made executor results concise structured summaries, preserving verbatim
  environment errors rather than relaying all output.
• Made direct installs explicit per host and recursive for skill resources.
• Adopted short-lived branches, protected main, and PR-only integration.
• Expanded the public documentation, examples, smoke tests, and release gates.

Fixed

• Preserve pre-existing working-tree changes when an executor fails; cleanup is
  limited to changes attributable to that dispatch.
• Stop cross-repo intake when permissions are insufficient instead of
  attempting sandbox workarounds.
• Remove stale files during direct skill synchronization.
• Reject unknown installer arguments and make --help side-effect free.
• Avoid handoff log collisions with agent/time filename suffixes.
• Keep optional OpenSpec design artifacts from blocking task generation.