feat: /autoplan — auto-review pipeline (v0.10.0.0) (#327)

* feat: /autoplan skill — auto-review pipeline with decision audit trail

Thin orchestrator that reads CEO, design, and eng review skills from disk
and runs them at full depth with auto-decisions using 6 encoded principles.
Surfaces taste decisions at a final approval gate.

* chore: wire /autoplan into routing, touchfiles, and validation tests

* chore: bump version and changelog (v0.10.0.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>