BattleTech egg builder, catalog, and golden-egg DiffTests (BT port phases 1-2)

New TeslaConsole.BattleTech namespace mirroring TeslaConsole.RedPlanet's
mission layer: BTMission/BTFreeForAllMission (egg serializer; RP wire framing
and ordinal bitmaps reused verbatim), BTParticipant/BTPlayer/BTCamera (BT
participant fields: advancedDamage, experience, vehicleValue, patch, role),
and the BTConfig/BTScenario/BTMap/BTVehicle/BTWeather/BTRole catalog loaded
from BattleTech\BTConfig.xml (reconstructed from the Mac Console 4.10 ini BT
tree). Free For All and No Return share one mission class - both send
scenario=freeforall; the mode is the role assigned to each pilot.

BTGoldenEggTests (7 tests, recovered-only) diff the generated egg
field-by-field against two eggs captured from the original consoles
(cavern.egg, TESTARN.EGG): order-independent per-section compare with
font-rendered bitmap pixel rows excluded, ordinal art byte-exact vs
TESTARN.EGG, EggFileMessage framing reassembly, role de-dup, No Return role
semantics, and shipped-catalog contents. Invoker gains BTEggString/
BTEggFraming reflection cases.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Console/tests/TeslaConsole.DiffTests/TeslaConsole.DiffTests.csproj

@@ -31,6 +31,11 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- BattleTech golden eggs captured from the original consoles (see BTGoldenEggTests). -->
+    <Content Include="BattleTech\*.egg" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
   <ItemGroup>
     <!--
       Build the reconstruction before the tests so we always compare against a fresh