Harden financial correctness and recovery boundaries

[nikitacometa]

Summary

• make asset payouts replay-safe with exact base-unit allocation, persisted signed intents, bounded fees, canonical network checks, and on-chain reconciliation
• replace blind LP read-modify-write and raw-balance pricing with crash-safe Decimal128 projections, strict uint64 boundaries, canonical supply provenance, and verified price chronology
• serialize staking lottery liabilities with atomic entitlements and fail-closed uniqueness indexes
• strengthen CI with Python 3.12/3.14, real MongoDB concurrency tests, production-image checks, and all-ref secret scanning
• align the public README, architecture notes, audit report, security policy, and task board with verified behavior

Verification

• make quality: 372 passed, 26 integration tests skipped without a configured MongoDB, 83.19% focused coverage
• isolated Python 3.12.8 and 3.14.6: 372 passed on each runtime
• disposable MongoDB: 26/26 integration scenarios passed
• Gitleaks 8.30.1: no findings across rewritten refs
• TruffleHog 3.95.9: 0 verified or unknown secrets across rewritten refs

Explicit follow-ups

One-of-one NFT inventory reservation remains gated behind disabled public lottery routes. Wallet-scoped authorization and async persistence remain tracked architecture work.