koios cache + stellar reserve fix

[Flotapponnier]

Summary

• Cardano: epoch params change once per 5-day epoch but both harnesses re-fetched every 30s/5min, blowing the shared 5,000/day koios public tier (429 Exceeded Tier Limit for days). 1h caches on both legs bring the combined load to ~48 calls/day, values unchanged (params are deterministic between epochs)
• Stellar token-deployment-cost: formula corrected from 3 to 5 base reserves (protocol minimum: 2 per new account x 2 accounts + 1 trustline). Stellar's figure rises ~$0.19 accordingly; methodology notes reserves are refundable locked capital, counted because issuance requires them upfront