Parse the GPS track and subtract aircraft acceleration from the gravity reference

The fix path for #45, from PR #51's attribution: the horizon dip (1.9-8.5 deg fitted amplitude) is the complementary filter's residual against an accelerometer measuring APPARENT gravity in coordinated flight. The file carries a GPS track (trailer record 7, 53 bytes/record per the format study; unparsed today). Parse it in kyerag-meta (PII note: GPS is exactly the data AGENTS.md bans from ever entering the repo - fixtures must be synthetic), derive centripetal + longitudinal acceleration from the track, subtract from the accel reference so the filter sees true gravity. Acceptance: kyerag-spike --bin dip fitted amplitude well under 1 deg on both X4 Air captures; the wrong-answer controls in that instrument already exist. Closes #45 when it lands.