Align docs with StyleGuide and add CLAUDE.md

- Rename 16 kebab-case docs to PascalCase per StyleGuide
- Move per-language client design docs from docs/ to clients/<lang>/
  alongside their READMEs
- Add ## Related Documentation sections to 15 docs that lacked one
- Fix sentence-case violations in H3 headings (StyleGuide rule)
- Update cross-references in gateway.md, client READMEs, scripts,
  and generate-proto.ps1 helpers to follow the new paths
- Add CLAUDE.md with build/test commands, the source-update
  verification matrix, the parity-first contract, and pointers
  to MXAccess and Galaxy Repository analysis sources

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

scripts/discover-testmachine-tags.ps1

@@ -36,7 +36,7 @@ if ($Attributes.Count -eq 0) {
 }
 
 if (-not (Test-Path -LiteralPath $SqlcmdPath)) {
-    throw "sqlcmd was not found at '$SqlcmdPath'. Pass -SqlcmdPath or update docs/toolchain-links.md."
+    throw "sqlcmd was not found at '$SqlcmdPath'. Pass -SqlcmdPath or update docs/ToolchainLinks.md."
 }
 
 $attributeList = ($Attributes | ForEach-Object {

scripts/publish-client-proto-inputs.ps1

@@ -22,7 +22,7 @@ function Resolve-Protoc {
         return $documentedPath
     }
 
-    throw "Could not find protoc.exe. See docs/toolchain-links.md for the documented protobuf toolchain path."
+    throw "Could not find protoc.exe. See docs/ToolchainLinks.md for the documented protobuf toolchain path."
 }
 
 function Ensure-Directory {