Extract shared contract, drop BinaryFormatter wire, modernize to net8/x64

Make the Console<->Launcher system source-built and modern now that the console
is under our control and the WinXP-era pods are gone.

Contract extraction (Contract/Tesla.Contract.csproj):
- One multi-targeted (net48;net8.0-windows) source project for the RPC contract,
  replacing the vendored TeslaConsoleLaunchLib.dll and the hand-synced Tesla.Net
  replica in Launcher/LaunchModels_Shared.cs. Emits assembly TeslaConsoleLaunchLib.

SecureConfig extraction (SecureConfig/Tesla.SecureConfig.csproj):
- net48 source of the first-boot provisioning protocol (UDP beacons, OFB crypto,
  RSA key exchange), replacing the vendored TeslaSecureConfiguration.dll.

Remove BinaryFormatter from the wire (RCE sink + the reason net6 was pinned):
- Console<->Launcher RPC is now length-prefixed System.Text.Json frames
  (Contract/PodRpcProtocol.cs) over the unchanged OFB transport; dispatch by
  method name. Deleted the SerializationBinder / MethodInfoProxy machinery.
- Console-local BinaryFormatter (Site config, mission replays) intentionally
  retained: local net48 file I/O, not the network surface.

Runtime modernization:
- Launcher Service + Agent: net6 -> net8, win-x86 -> win-x64 (all pods are
  64-bit Win10). Kept the SHA1-default PBKDF2 (Console key-derivation compat)
  with SYSLIB0041 suppressed and documented.

Tests: differential suite now 73 green. Added SecureConfigCompatTests (OFB
ciphertext byte-identical to the vendored DLL) and PodRpcProtocolTests (JSON
round-trip of every request/response shape); removed the now-obsolete
BinaryFormatter byte-identity guard.

Build hygiene: per-project obj dirs (Launcher/Directory.Build.props) fix a
NuGet restore collision between the two Launcher projects sharing one folder.

NOT runtime-verified against a live pod.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SecureConfig/Tesla.SecureConfig.csproj

@@ -0,0 +1,28 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <!-- net48 only: consumed by the net48 Console and the net48 client half of
+         Tesla.Contract. The pod side is the Launcher's own SecureConfig.cs. -->
+    <TargetFramework>net48</TargetFramework>
+
+    <!-- Emit an assembly named TeslaSecureConfiguration (v1.0.0.0) so it is a
+         drop-in replacement for the original vendored binary. Unlike the wire
+         contract this is not strictly required for compatibility (the provisioning
+         protocol uses manual byte/AES/RSA serialization, not BinaryFormatter), but
+         keeping the identity stable avoids surprising any name-based resolution. -->
+    <AssemblyName>TeslaSecureConfiguration</AssemblyName>
+    <RootNamespace>Tesla</RootNamespace>
+    <AssemblyVersion>1.0.0.0</AssemblyVersion>
+    <FileVersion>1.0.0.0</FileVersion>
+    <Version>1.0.0.0</Version>
+
+    <Nullable>disable</Nullable>
+    <ImplicitUsings>disable</ImplicitUsings>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" PrivateAssets="all" />
+  </ItemGroup>
+
+</Project>