Closes the caveat I flagged in c9dc8dd. savegame.rs documents the chunk stream
(read off the title's own serializer at 0x822C00E8) as GDAA / phase string /
'GHAD' + 122 bytes / SHAB table, and FieldSpec.offset is "offset within the
122-byte GHAD block" -- so the base is the byte after the tag, tag+4.
Reading there yields three fields, two corroborated independently elsewhere in the
corpus: Stage +52 = 2, Points +24 = 4101 (weapon-datasheet-runtime.md's "4101 P"),
FlightTime +4 = 324773 (the 05:24.77 Stage-01 best time). tag+8 reproduced only
the stage. The payload's phase string reads GP_BUNK.
Left open: the .header mirror does not reproduce -- savegame.rs lists Stage at
header offset 0x14 but a BE u32 there reads 2097200 (00 20 00 30), which looks
like UTF-16 text. Not chased; the payload reading does not depend on it.
67001f04fb