Fix RDD lifecycle consistency and skill handoffs

[mattias-modernpath]

Stack

Stacked on #17. The base is feature/flat-engineering-constraints, not main; this PR contains only the follow-up fixes.

Findings addressed

1. Preserve historical RED as role-specific RETAINED evidence, separate from current passing/regression evidence. Serialize each immutable run and its append-only validity assessments independently.
2. Define scoped corrective demotions and a build route for upper-flow, review, and engineering failures after behavioral tests pass. Keep unchanged entry authority and block integration until candidate checks pass.
3. Make delivery guards work with mixed-state selections; preserve unchanged reviewed and DONE members.
4. Define acyclic fingerprint input manifests that exclude each gate’s own outputs while retaining declared prerequisite references.
5. Make adoption campaigns resumable across bounded contexts without duplicating candidates or overwriting confirmed records.
6. Apply valid answered release decisions before enforcing single-active-release selection; serialize registry state and decision inputs.
7. Preserve per-item suspended-from state and reassess evidence when releasing holds.
8. Check canonical TEST references, complete supported names and subtest components; expose unsupported syntax, exemptions, missing roots, and zero-check results instead of silently passing.

Skill usability

• Add explicit input/write/exit contracts and durable next-action handoffs to all focused skills.
• Specify the independent cold-review context and artifact handoff.
• Move the lengthy audit examples into an optional supporting reference while preserving them.
• Separate ModernPath ingestion/command conventions and recovered-design guidance from the core adoption procedure.
• Include repeatable lifecycle forward-test scenarios and evidence-migration guidance.

Validation

• Observed failing citation regression tests against the previous implementation; committed the tests before the fixes.
• node --test tests/*.test.mjs: 20 passing tests.
• All 13 skills pass the skill-creator structural validator.
• Markdown fences balanced across 27 files; 12 local links resolve.
• git diff --check passes.
• Independent read-only forward simulation of nine lifecycle cases; two residual wording conflicts corrected and independently rechecked.

The lifecycle scenarios validate instruction execution through review, not a live process-store implementation. Citation name checks establish lexical presence, not test registration, execution, or behavioral proof.