XP11: single net40 binary runs on XP SP3 through Windows 11

Merge TeslaLauncherService (Session 0) + TeslaLauncherAgent (tray) into one
userland TeslaLauncher.exe. The split existed only to work around Vista+
Session 0 isolation; running everything in the auto-logged-in admin session
needs no service, no named pipe, and no flat<->wire conversion layer. The
original Elsewhen software was likewise a single binary.

net40 is the newest framework XP SP3 can install, and net40 assemblies load
in-place on the 4.8 runtime in Win10/11 -- one exe covers both.

- Contract: multi-target net48;net40. The net40 leg of PodRpcProtocol uses
  Newtonsoft.Json (STJ has no net40 target); JSON is shape-identical on the
  wire, and the request reader keeps date strings raw so Ping echoes
  byte-identically. Console keeps the untouched net48/STJ leg.
- MiniZip.cs: central-directory ZIP extractor (stored/deflate/ZIP64) since
  net40 has no ZipFile; zip-slip guarded.
- SecureConfig: RSACryptoServiceProvider instead of RSA.Create (net46+),
  no leaveOpen BinaryWriter/Reader, struct instead of ValueTuple, and no
  SetCompatibleTextRenderingDefault on the passcode thread (the merged app
  already has a form). netsh "interface ip" syntax was already XP-correct.
- Volume: nircmd -> CoreAudio (Vista+) -> winmm waveOutSetVolume (XP).
- Paths: CommonApplicationData resolved per-OS (XP has no C:\ProgramData);
  launcher log moved next to the key/config in the data dir.
- install.bat: dual-OS (cacls/icacls, netsh firewall/advfirewall, dism and
  UAC/notification steps skipped on XP, .NET 4.0 redist check, XP DHCP reset
  via netsh); no service registration -- HKLM Run key + auto-login on both;
  RegisterApplicationRestart supplies crash-restart on Vista+.
- Bench switches: /skipconfig, /port:NNNN.

Verified: Console + diff suite (103 tests) still green on the net48 leg;
E2E smoke test drove the net40 launcher over real TCP with the Console's own
PodManagerConnection (STJ client vs Newtonsoft server) -- Ping echo, volume,
app registry, launch/kill/watch, InstallProduct zip transfer + extract, and
uninstall orphan cleanup: 17/17 pass.

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

Contract/PodRpcProtocol.cs

@@ -16,10 +16,22 @@
 // one file, so the request/response shape cannot drift.
 // =============================================================================
 
+// NET40 (XP11 single-binary launcher): System.Text.Json has no net40 target, so
+// this leg serializes with Newtonsoft.Json instead. Same framing, same JSON shape
+// (PascalCase member names, fields included, Guids as strings, ISO-8601 dates) —
+// an STJ client and a Newtonsoft server interoperate byte-compatibly on the wire.
+// Arguments surface as JToken here instead of JsonElement.
+
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Text;
+#if NET40
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+#else
 using System.Text.Json;
+#endif
 
 namespace Tesla.Net
 {
@@ -27,13 +39,21 @@ namespace Tesla.Net
     public sealed class RpcRequest
     {
         public string Method { get; set; }
+#if NET40
+        public List<JToken> Args { get; set; }
+#else
         public List<JsonElement> Args { get; set; }
+#endif
     }
 
     /// <summary>One RPC result: the return value as JSON, or an error message.</summary>
     public sealed class RpcResponse
     {
+#if NET40
+        public JToken Result { get; set; }         // JSON null for void / null
+#else
         public JsonElement Result { get; set; }   // JsonValueKind.Null for void / null
+#endif
         public string Error { get; set; }          // null on success
     }
 
@@ -45,12 +65,18 @@ namespace Tesla.Net
         /// streamed out-of-band, not framed), guarding against hostile lengths.</summary>
         public const int MaxFrameBytes = 16 * 1024 * 1024;
 
+#if NET40
+        // Newtonsoft serializes public fields of the wire types by default, and
+        // writes ISO-8601 dates / string Guids like STJ — no special options needed.
+        public static readonly JsonSerializer JsonOptions = JsonSerializer.CreateDefault();
+#else
         public static readonly JsonSerializerOptions JsonOptions = new JsonSerializerOptions
         {
             // The Tesla.Net wire types (LaunchData, LaunchPair, ...) expose public
             // FIELDS, which System.Text.Json ignores unless this is set.
             IncludeFields = true,
         };
+#endif
 
         // ── Framing ──────────────────────────────────────────────────────────
 
@@ -88,6 +114,25 @@ namespace Tesla.Net
 
         // ── Request ──────────────────────────────────────────────────────────
 
+#if NET40
+        public static void WriteRequest(Stream stream, string method, object[] args)
+        {
+            var req = new RpcRequest { Method = method, Args = new List<JToken>() };
+            if (args != null)
+                foreach (var a in args)
+                    req.Args.Add(a == null ? JValue.CreateNull() : JToken.FromObject(a, JsonOptions));
+            WriteFrame(stream, Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(req)));
+        }
+
+        public static RpcRequest ReadRequest(Stream stream)
+            => JsonConvert.DeserializeObject<RpcRequest>(
+                Encoding.UTF8.GetString(ReadFrame(stream)), ReadSettings);
+
+        // Keep date-looking strings as raw strings so an echoed argument (Ping)
+        // goes back byte-identical instead of reformatted through DateTime.
+        private static readonly JsonSerializerSettings ReadSettings =
+            new JsonSerializerSettings { DateParseHandling = DateParseHandling.None };
+#else
         public static void WriteRequest(Stream stream, string method, object[] args)
         {
             var req = new RpcRequest { Method = method, Args = new List<JsonElement>() };
@@ -99,9 +144,26 @@ namespace Tesla.Net
 
         public static RpcRequest ReadRequest(Stream stream)
             => JsonSerializer.Deserialize<RpcRequest>(ReadFrame(stream), JsonOptions);
+#endif
 
         // ── Response ─────────────────────────────────────────────────────────
 
+#if NET40
+        public static void WriteResponse(Stream stream, object result, string error)
+        {
+            object payload = error == null ? result : null;
+            var resp = new RpcResponse
+            {
+                Result = payload == null ? JValue.CreateNull() : JToken.FromObject(payload, JsonOptions),
+                Error = error,
+            };
+            WriteFrame(stream, Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(resp)));
+        }
+
+        public static RpcResponse ReadResponse(Stream stream)
+            => JsonConvert.DeserializeObject<RpcResponse>(
+                Encoding.UTF8.GetString(ReadFrame(stream)), ReadSettings);
+#else
         public static void WriteResponse(Stream stream, object result, string error)
         {
             var resp = new RpcResponse
@@ -116,5 +178,6 @@ namespace Tesla.Net
 
         public static RpcResponse ReadResponse(Stream stream)
             => JsonSerializer.Deserialize<RpcResponse>(ReadFrame(stream), JsonOptions);
+#endif
     }
 }