fix(mh3g): preserve companion mask mastery state

[VincentAdamNemessisX]

Summary

• correct the Cha-Cha/Kayamba record schema from one u32 prefix plus u16 scalars, instead of three u32 header fields
• preserve the complete packed mask/mastery block at relative offsets 0xDE..0x140, including the historically mis-swapped pair at 0xE4
• keep 0.0.3-0.0.6 conversion replay byte-identical for version detection, then repair matching historical fields without reverting later Wii U progress
• update compatibility-field granularity, docs, played-save fixture boundaries, and the disabled legacy-wrapper markers

Root cause

The previous Lamp Mask fix inferred that companion-relative 0xE4 was an isolated endian-sensitive u16. Five paired 3DS -> Wii U transfer samples disprove that assumption: 0xDE..0x140 is byte-packed and remains identical on both platforms. The old transform changed values such as 18 00 into 00 18, so the companion status path observed a leading zero; quest serialization could then write zero back into the mask state.

The same paired samples also show that relative 0x04..0x0B consists of four u16 values, not two u32 values.

Evidence

• cargo test -p mh3g-save-convert: 220 passed
• native and x86_64-pc-windows-msvc clippy with -D warnings: passed
• macOS Swift tests: 72 passed
• macOS packaged-app synthetic smoke: passed
• documentation and Windows source contracts: passed
• supplied archive SHA-256: 0262a4c5353deca35fa1220d89c87414383bab1454509d06d14d6414f7827712
• five paired saves, two companions each: zero byte differences across the confirmed 0x000..0x13F companion schema; packed 0xDE..0x13F equals the 3DS source in all ten records
• real-sample compatibility repair detected 0.0.6 exactly, repaired ten companion fields, produced the same SHA-256 as a fresh corrected conversion (a1815a838bbe45cf33fc6db41efc4d5b438b53d7f6bc7d1704b78d56879b562c), and rollback removed the separate output successfully

Validation boundary

• no Cemu gameplay/runtime test was performed
• no real Azahar/Nemessix/Cemu MLC was modified
• an already quest-normalized 00 00 conflict is preserved fail-closed; forcing recovery requires a paired before/after snapshot rather than guessing over later Wii U progress

[VincentAdamNemessisX]

Superseded by #44. The mask/mastery fix is preserved there with the same stable patch-id, together with the paired-transfer Hunter's Notes correction and Windows repair-flow regression fix. Closing this standalone PR avoids a duplicate auto-release; attribution is retained in the cherry-picked commit.