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-ablegacy-smoke.sql

@@ -9,7 +9,7 @@
 -- after) before running the seed for that setup.
 --
 -- Usage:
---   docker compose -f tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/Docker/docker-compose.yml --profile slc500 up -d
+--   docker compose -f tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.IntegrationTests/Docker/docker-compose.yml --profile slc500 up -d
 --   sqlcmd -S "localhost,14330" -d OtOpcUaConfig -U sa -P "OtOpcUaDev_2026!" \
 --          -i scripts/smoke/seed-ablegacy-smoke.sql