[ ProtocolSparkle/Sparkle-Protocol ] v1.2.0 - Critical Security Fixes (Gemini + Codex Audits)

CRITICAL FIXES:

- Inverted preimage flow: buyer now generates preimage (fixes seller theft vulnerability)

- Safety buffer: 12 -> 72 blocks (fixes time-bandit attack)

- Gate 2 dust padding: Output >= Input (fixes sub-dust ordinals)

- BIP-371 PSBT: type 0x15 -> 0x16, key/value corrected (fixes wallet rejection)

- Sequence alignment: 0xfffffffe -> 0xfffffffd in PSBT summary

NEW FEATURES:

https://github.com/ProtocolSparkle/Sparkle-Protocol/commit/86b4fa72edbd7b6253ad30759eaacf3ef839212d