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-s7-smoke.sql

@@ -1,7 +1,7 @@
 -- S7 e2e smoke seed — closes #212 (umbrella #209).
 --
 -- One-cluster seed pointing at the python-snap7 fixture
--- (`docker compose -f tests/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/Docker/docker-compose.yml --profile s7_1500 up -d`).
+-- (`docker compose -f tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.IntegrationTests/Docker/docker-compose.yml --profile s7_1500 up -d`).
 -- python-snap7 listens on port 1102 (non-priv); real S7 CPUs listen on 102.
 -- Publishes one Int16 tag at DB1.DBW0 under `ns=<N>;s=DB1_DBW0` (driver
 -- sanitises the dot for browse names — see S7Driver.DiscoverAsync).
@@ -123,5 +123,5 @@ PRINT 'Next steps:';
 PRINT '  1. Set src/.../Server/appsettings.json Node:NodeId = "s7-smoke-node"';
 PRINT '                                          Node:ClusterId = "s7-smoke"';
 PRINT '  2. docker compose -f tests/.../S7.IntegrationTests/Docker/docker-compose.yml --profile s7_1500 up -d';
-PRINT '  3. dotnet run --project src/ZB.MOM.WW.OtOpcUa.Server';
+PRINT '  3. dotnet run --project src/Server/ZB.MOM.WW.OtOpcUa.Server';
 PRINT '  4. ./scripts/e2e/test-s7.ps1 -BridgeNodeId "ns=2;s=DB1_DBW0" -S7Host "127.0.0.1:1102"';