feat: solana-validator-ops-skill — stake activation math, validator health monitoring, merge pre-check

[atharv404]

Fills the only major gap in the kit nobody else has covered: validator & stake-pool ops.

Core problems solved:

• getStakeActivation was removed from the JSON RPC ; this skill reimplements the warmup/cooldown algorithm client-side (src/stakeActivation.js)
• Credit-delta delinquency detection catches validator degradation 1–2 epochs before the on-chain delinquent flag trips
• Stake merge MergeKind compatibility pre-check prevents wasted compute budget on failed on-chain merges
• Commission-change detection (snapshot-based) catches the "low commission rug" pattern that has no on-chain event

Ships with: 44 unit tests, zero dependencies, runs with npm test on any Node ≥ 18.

Repo: https://github.com/atharv404/solana-validator-ops-skill