e2e: cover docs init-feature artifact contract

[codeaholicguy]

Current coverage

No E2E invokes docs init-feature.

What is missing

• Date-prefixed files for all configured phases
• Custom docs directory handling
• Human and --json path output
• Existing-file collision safety
• Invalid/normalized feature names
• Missing/uninitialized configuration behavior

Risk ranking

Medium-low, rank 12: lifecycle artifacts are central to the workflow, although the command has lower operational blast radius.

Recommended E2E tests

• Assert configured phases/docs directory produce date-prefixed files, JSON paths, collision safety, and invalid-name rejection.

Acceptance criteria

• The checklist test is merged under e2e/.
• File names, frontmatter/content source, JSON schema, and non-overwrite behavior are asserted.
• Default and custom docs directories are covered.

Related audit findings

D1 and issue #77: multi-repo workspace guidance must define which repository owns lifecycle docs.