Add MW4COMPARE: .mw4 decompiler toolchain and V4H comparison harness

Tooling built to recover editable source for six 'Mech chassis that exist
in the parallel FS_Build_V4H build but not in this repo. Reverse-engineers
every compiled record type in the .mw4 package format back to the .data /
.instance / .subsystems / .damage / .contents / .torso / .engine /
.armature sources the content pipeline consumes.

Nothing here is wired into the game build. It is a standalone analysis
harness run from Linux.

Package format
--------------
"#VBD" container. Directory records are [len][name][FILETIME][origSize]
[storedSize][offset], payload base at dword 0x0C. A record is stored raw
when storedSize == origSize, otherwise LZW (9->12-bit LSB-first codes,
256=clear, 257=EOF, dict from 258), per Database.cpp:451.

GameModel records are flat /Zp4 structs following the C++ inheritance
chain Entity(0) -> Mover(28) -> MWObject(80) -> Vehicle(664) -> Mech(756),
1636 bytes total. CreateMessage records follow Replicator -> Entity ->
Mover -> MWMover -> MWObject -> Vehicle -> Mech from start=16 (the
undeclared Connection__Message header), ending at 341 and padded to 344.

tools/decompile/
----------------
  datamap.py        header-driven layout engine; CHAIN + ANCHORS
                    {Vehicle:664, Mech:756} assert the struct offsets
  mw4msg.py         CreateMessage reader/walker
  data.py           .data      constants.py  define/table symbol resolution
  damage.py         .damage    contents.py   .contents
  smallmodel.py     .torso + .engine         instance.py  .instance
  armature.py / armature_parts.py  .armature + armaturedata/armaturevideo
  assembly.py       joint hierarchy renderer
  make_generic_doll.py  builds generic MFD/Radar damage dolls
  verify_*.py       per-type round-trip verifiers

Verified round-trip across all 64 shared chassis:
  .armature      2938/2976 pages     .subsystems  7579/7585 keys
  .data map      6071/6071 values    .data trip   8291/8306 keys
  .damage        6605/6605 keys      .contents    7480/7480 keys
  .torso+.engine 1280/1280 keys      .instance     896/896 keys, 64/64 pages
  armature_parts 1202/1202 .data, 1149/1202 .video

Layout-discovery lessons (documented in DECOMPILING.md)
-------------------------------------------------------
- Never let a field map be discovered by the values that verify it. A
  value-matching pass reported 4288/4288 while mis-assigning 34 keys. The
  map was rebuilt from header declaration order, anchored on uniquely
  resolved fields.
- Read the factory, not the data. 12 .data fields and 5 Torso fields are
  declared plain Stuff::Scalar but multiplied by Radians_Per_Degree in
  Mech_Tool.cpp:889 / Torso_Tool.cpp.
- Strip typedefs before walking a header. A stray `typedef int AttributeID;`
  masked a missing ClassID - two 4-byte errors cancelling out, caught only
  by the ANCHORS assertion.
- A verifier that silently narrows its own input reports success. Braced
  blocks must be hidden before splitting pages, replacing both CR and LF,
  because a `Shadow={...}` block contains a line reading `[shadow]` and
  splitlines() also splits on bare CR.
- NSWIZZLE is undefined, so the #else branch is live and orders members
  differently. bool is 1 byte; char x[MaxStringLength] is 256.
- V4H carries stale Mech IDs (their Atlas is 5, ours 6), so 64 of 65 shared
  chassis are off by one; --retarget-ids emits $(M_<Chassis>)/$(IDS_<Chassis>).

reports/ holds generated diffs. The two ~5 MB manifest-*.tsv intermediates
are gitignored; regenerate everything with run-comparison.sh.

Co-authored-by: Claude Opus 5 (Anthropic) <noreply@anthropic.com>
Co-authored-by: GitHub Copilot <copilot@github.com>

MW4COMPARE/reference/options.ini.diff

@@ -0,0 +1,90 @@
+6,7c6,7
+< playericon=Content\Textures\stockdecals\decal_48.tga
+< teamicon=Content\Textures\stockdecals\decal_48.tga
+---
+> playericon=Content\Textures\stockdecals\decal_49.tga
+> teamicon=Content\Textures\stockdecals\decal_50.tga
+29c29
+< bitdepth=16
+---
+> bitdepth=32
+56c56
+< visibility=1
+---
+> visibility=0
+60c60
+< heaton=0
+---
+> heaton=1
+68,69c68,69
+< unlimitedammo=1
+< friendlyfirepercentage=0
+---
+> unlimitedammo=0
+> friendlyfirepercentage=100
+79c79
+< ruletype=2
+---
+> ruletype=17
+84c84
+< allowedbeam1=ffffffff
+---
+> allowedbeam1=fffffffd
+86c86
+< allowedmissile1=ffffffff
+---
+> allowedmissile1=ff3bffff
+88c88
+< allowedprojectile1=ffffffff
+---
+> allowedprojectile1=ffffdfff
+112c112
+< lrpt=072003082ab4b906fabd1c154d3d8fd77942028e
+---
+> lrpt=032020102ab4b906fabd1c154d3d8fd77942028e
+115,118c115
+< RuleBook=1
+< DawnWar=1
+< BiggieSizeIt=1
+< CanYouHearTheFootSteps=1
+---
+> 
+144,181d140
+< 
+< [RookieMission]
+< // Default mission loaded when the console opens and when "Default" is clicked.
+< // All entries are optional - omit any to keep the hardcoded built-in default.
+< //
+< // MissionName   - exact display name as it appears in the map dropdown
+< //                 default: ScarabStronghold - Attrition
+< // GameType      - 0-based index into the game-type dropdown (2 = Attrition)
+< //                 default: 2
+< // TimeLimit     - time limit in minutes; -1 means use the server's default time
+< //                 default: -1 (uses g_nTimeList_Value, currently 7 min)
+< // Visibility    - 0=Clear 1=Light Fog 2=Medium Fog 3=Heavy Fog
+< // Weather       - 0=Off 1=Rain
+< // TimeOfDay     - 0=Day 1=Night
+< // Radar         - 0=Novice 1=Off 2=Bars 3=Unlimited
+< // HeatOn        - 0=Off 1=On
+< // FriendlyFire  - 0=Off 100=Full (percentage)
+< // SplashDamage  - 0=Off 1=On
+< // UnlimitedAmmo - 0=Off 1=On
+< // WeaponJam     - 0=Off 1=On
+< // AdvanceMode   - 0=Off 1=On
+< // ArmorMode     - 0=Off 1=On
+< //
+< // Example: uncomment and edit lines below to customize
+< //MissionName=ScarabStronghold - Attrition
+< //GameType=2
+< //TimeLimit=-1
+< //Visibility=0
+< //Weather=0
+< //TimeOfDay=0
+< //Radar=0
+< //HeatOn=0
+< //FriendlyFire=0
+< //SplashDamage=0
+< //UnlimitedAmmo=1
+< //WeaponJam=0
+< //AdvanceMode=0
+< //ArmorMode=0