feat: define Integrate governance preset

[devkade]

Summary

Define Integrate as an integration-governance preset in the RunContract Harness.

Parent roadmap: #114
Track: C - Preset evolution
Related: #118, #167

Problem

Integrate is the preset for merging, conflict handling, and integration verification, but its RunContract-facing governance contract is not explicit. Without it, integration work can blur source-of-truth ownership, evidence requirements, and repair/rollback criteria.

Scope

• Define the Integrate governance preset contract.
• Specify required inputs, integration plan shape, conflict matrix expectations, evidence standard, verification gates, and rollback/repair criteria.
• Define how Integrate consumes upstream implementation artifacts without becoming a generic scheduler or PR adapter.
• Keep integration governance generic and separate from GitHub/PR/Ragna/kapi-agent semantics.
• Identify follow-up implementation slices if existing Integrate behavior needs alignment.

Non-goals

• No merge bot implementation.
• No GitHub/PR-specific policy in RunContract core.
• No worker scheduler or policy-learning implementation.
• No command rename or storage-root migration.
• No broad workflow-state rename.

Acceptance criteria

• Integrate preset contract is documented or implemented with tests.
• Integration plan, conflict matrix, evidence, and verification expectations are explicit.
• Repair/rollback criteria are defined.
• Upstream artifact consumption is specified without duplicating source-of-truth state.
• The preset remains generic and adapter-neutral.

Verification

• Design review against Kapi → Ilchul RunContract Harness roadmap #114 RunContract boundary.
• Review against existing Integrate artifact conventions.
• Relevant Integrate workflow tests if implementation changes are included.