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>

scripts/smoke/seed-phase-7-smoke.sql

@@ -174,7 +174,7 @@ PRINT '  Node:       ' + @NodeId + ' (set Node:NodeId in appsettings.json)';
 PRINT '  Generation: ' + CONVERT(nvarchar(20), @Gen);
 PRINT '';
 PRINT 'Next steps:';
-PRINT '  1. Edit src/ZB.MOM.WW.OtOpcUa.Server/appsettings.json:';
+PRINT '  1. Edit src/Server/ZB.MOM.WW.OtOpcUa.Server/appsettings.json:';
 PRINT '       Node:NodeId      = "p7-smoke-node"';
 PRINT '       Node:ClusterId   = "p7-smoke"';
 PRINT '  2. Edit the placeholder Galaxy attribute in dbo.Tag.TagConfig above';
@@ -182,5 +182,5 @@ PRINT '       so it points at a real attribute on this Galaxy — replace';
 PRINT '       REPLACE_WITH_REAL_GALAXY_ATTRIBUTE with e.g. "Plant1.Reactor1.Temp".';
 PRINT '  3. Start the Server in a non-elevated shell so the Galaxy.Host pipe ACL';
 PRINT '       accepts the connection:';
-PRINT '       dotnet run --project src/ZB.MOM.WW.OtOpcUa.Server';
+PRINT '       dotnet run --project src/Server/ZB.MOM.WW.OtOpcUa.Server';
 PRINT '  4. Validate via Client.CLI per docs/v2/implementation/phase-7-e2e-smoke.md';