feat: release Sol Advisor 0.5.2 orchestration contract

[atomrq]

Summary

• Make the capability-gated GPT-5.6 Luna / Max app-task lane the default independent, subagent-like, user-visible execution lane.
• Make the Sol leader own scheduling, monitoring, corrections sent to the same task, independent review, and acceptance.
• Retain the native Terra implementer / fresh Sol reviewer lane with its exact routing.
• Align 0.5.2 metadata and runtime surfaces across the Codex manifest, canonical Agent Plugins v1 manifest, package.json, MCP runtime/tests, setup compatibility guidance, and changelog.

Validation

• sh plugins/sol-advisor/scripts/verify.sh — PASS
• bun test — 39 pass, 0 fail
• bun run validate — PASS
• git diff --cached --check — PASS before commit
• Shipped-surface stale-claim scan — no shipped contradiction

Release boundary

No tag or GitHub Release was created. This PR does not include package/release/build or plugin-install work.