chore: organize solution into module folders (Core/Server/Drivers/Client/Tooling)

Group all 69 projects into category subfolders under src/ and tests/ so the
Rider Solution Explorer mirrors the module structure. Folders: Core, Server,
Drivers (with a nested Driver CLIs subfolder), Client, Tooling.

- Move every project folder on disk with git mv (history preserved as renames).
- Recompute relative paths in 57 .csproj files: cross-category ProjectReferences,
  the lib/ HintPath+None refs in Driver.Historian.Wonderware, and the external
  mxaccessgw refs in Driver.Galaxy and its test project.
- Rebuild ZB.MOM.WW.OtOpcUa.slnx with nested solution folders.
- Re-prefix project paths in functional scripts (e2e, compliance, smoke SQL,
  integration, install).

Build green (0 errors); unit tests pass. Docs left for a separate pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests/DL205/DL205ExceptionCodeTests.cs

@@ -0,0 +1,53 @@
+using Shouldly;
+using Xunit;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests.DL205;
+
+/// <summary>
+///     Verifies the driver's Modbus-exception → OPC UA StatusCode translation end-to-end
+///     against the dl205.json pymodbus profile. pymodbus returns exception 02 (Illegal Data
+///     Address) for reads outside the configured register ranges, matching real DL205/DL260
+///     firmware behavior per <c>docs/v2/dl205.md</c> §exception-codes. The driver must surface
+///     that as <c>BadOutOfRange</c> (0x803C0000) — not <c>BadInternalError</c> — so the
+///     operator sees a tag-config diagnosis instead of a generic driver-fault message.
+/// </summary>
+[Collection(ModbusSimulatorCollection.Name)]
+[Trait("Category", "Integration")]
+[Trait("Device", "DL205")]
+public sealed class DL205ExceptionCodeTests(ModbusSimulatorFixture sim)
+{
+    [Fact]
+    public async Task DL205_FC03_at_unmapped_register_returns_BadOutOfRange()
+    {
+        if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);
+        if (!string.Equals(Environment.GetEnvironmentVariable("MODBUS_SIM_PROFILE"), "dl205",
+                StringComparison.OrdinalIgnoreCase))
+        {
+            Assert.Skip("MODBUS_SIM_PROFILE != dl205 — skipping.");
+        }
+
+        // Address 16383 is the last cell of hr-size=16384 in dl205.json; address 16384 is
+        // beyond the configured HR range. pymodbus validates and returns exception 02
+        // (Illegal Data Address).
+        var options = new ModbusDriverOptions
+        {
+            Host = sim.Host,
+            Port = sim.Port,
+            UnitId = 1,
+            Timeout = TimeSpan.FromSeconds(2),
+            Tags =
+            [
+                new ModbusTagDefinition("Unmapped",
+                    ModbusRegion.HoldingRegisters, Address: 16383,
+                    DataType: ModbusDataType.UInt16, Writable: false),
+            ],
+            Probe = new ModbusProbeOptions { Enabled = false },
+        };
+        await using var driver = new ModbusDriver(options, driverInstanceId: "dl205-exc");
+        await driver.InitializeAsync("{}", TestContext.Current.CancellationToken);
+
+        var results = await driver.ReadAsync(["Unmapped"], TestContext.Current.CancellationToken);
+        results[0].StatusCode.ShouldBe(0x803C0000u,
+            "DL205 returns exception 02 for an FC03 at an unmapped register; driver must translate to BadOutOfRange (not BadInternalError)");
+    }
+}