platform_engineer/release_builder should ask for release policy before automation

[ncrmro]

Summary

platform_engineer/release_builder still tends to jump too quickly from release audit into workflow setup. It should first force the user to define the repository's release policy, then implement automation that matches that policy.

Problem

The current flow can produce a technically valid release pipeline while still missing critical product-level release decisions. Keystone exposed this gap.

Examples of policy questions that materially affect the implementation:

• release cadence
• version semantics for major/minor/patch
• stabilization model and duration
• backport policy
• hotfix policy
• merge-back policy
• publish targets
• stable vs unstable consumer guidance

Without these answers, the job can overfit to defaults or infer a release model from tooling rather than user intent.

Desired behavior

platform_engineer/release_builder should:

• detect which release-policy decisions are already explicit in repo docs and automation
• treat unresolved policy decisions as audit gaps
• ask the user to resolve those gaps before configuring automation
• record the chosen release policy in release_docs.md
• ensure the resulting CI workflow, branch rules, and docs implement the chosen policy rather than implicit defaults

Acceptance criteria

• audit_release explicitly reports unresolved release-policy questions
• setup_release_pipeline refuses to proceed on implicit defaults when policy decisions remain ambiguous
• the workflow asks about cadence, version semantics, stabilization, backports, hotfixes, merge-back, publish targets, and stable vs unstable guidance when not already explicit
• release_docs.md includes a dedicated release-policy section
• generated automation is validated against the chosen policy

Context

This came from running platform_engineer/release_builder against Keystone. The release branch mechanics were implemented, but the job should have interviewed the user more deeply about the release contract before writing the automation.