v1.4: test clean KFPS 3.1.31 livery decoder

[Datamining00]

Goal

Replace the pinned KFPS 3.1.27 backend with KFPS 3.1.31 (004b3b61a57d901e65957b6099805835f91e32f6) for an A/B test, and remove FH6 Assistant's decoder-side recovery stack from runtime.

Clean-decoder policy

This branch does not install:

• compact-shape guard;
• populated-section boundary override;
• decoder recovery;
• bare-parent transform fix;
• consecutive-transform-pair fix;
• structural parser audit;
• source-offset layer-order normalization.

The established v1.4 rendering/UI pipeline remains enabled. Warning-only integrity handling and persistent preview scale are retained through a small clean-baseline wrapper that deliberately does not rewrite decoder order. Clean-decoder cache identities are isolated so stale previews from the previous parser cannot be reused.

Why

KFPS 3.1.31 upstream reworked FH6 full-livery stream decoding and validated scene semantics against ForzaLiveryStudio across a large local corpus. This branch tests whether the upstream decoder now supersedes the local parser patches.

Build notes

• vendors exact KFPS commit 004b3b61a57d901e65957b6099805835f91e32f6;
• includes the new kfps_shapes package required by current json_preview_renderer.py;
• adds a smoke test that verifies the 3.1.31 occupancy model and rejects unknown framed shape word 0x0100 as a native shape;
• legacy patch unit tests remain available, but their app-wiring assertions recognize that this clean branch intentionally does not install those patches.

Startup regression fixed

The first clean-decoder EXE crashed during startup because the wrapper called a non-existent helper baseline._install_scale_persistence(). The actual helper in the baseline module is baseline._install_scale_persistence_and_warning_ui().

The wrapper now calls the existing helper, and a regression test explicitly checks that the startup wrapper references a real function and does not reintroduce the obsolete name.

Current validation

• Windows CI: success (32388631530)
• Regression suite: 189 tests, OK
• PyInstaller one-file build: success
• EXE bytes: 82,640,239
• EXE SHA-256: 52bf2e3877bb94600b6fbf834a93d9917ca9634b79b3cc9e6a41beec2c5dd5a0
• Artifact ZIP SHA-256: d447d9a3e173a47bc7c40bfa23aceea9b6eea29b77e7bd89dabf00e6b6c6c406

Draft until the previously problematic real liveries are visually checked. Do not merge before that verification.