feat: Hacash Mining Profitability Calculator

[enioxt]

Problem

GPU miners for Hacash were just released (Feb 2026, by Iv — PR #42 to hacash/fullnode). The community is excited but has no tool to calculate profitability. No mining calculator exists for Hacash anywhere.

Proposal

Build a mining profitability calculator at egos.ia.br/tools/hacash-mining

Features

• HAC mining calculator (input: hashrate, electricity cost, pool fee → output: HAC/day, USD/day)
• HACD mining estimator (time to find diamond, bid cost analysis)
• Current network stats (difficulty, hashrate, block reward) auto-fetched
• Historical difficulty chart
• CPU vs GPU comparison table
• Break-even analysis

Data Sources

• Hacash RPC for difficulty, hashrate, block reward
• CoinGecko API for HAC/USD price
• Community benchmarks for hashrate by hardware

No Duplication

• miningpoolstats.stream/hacash shows pool stats but NO calculator
• hacash.diamonds has mining pool but NO profitability tool

PRD: docs/plans/HACASH_COMMUNITY_TOOLS_PRD.md — Project 2