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>

docs/ClientPackaging.md

@@ -2,7 +2,7 @@
 
 This document defines the clean-checkout commands for building, packaging, and
 running the official MXAccess Gateway clients. Use the tool paths and versions
-in [Toolchain Links](./toolchain-links.md) when a command is missing from
+in [Toolchain Links](./ToolchainLinks.md) when a command is missing from
 `PATH`.
 
 ## Shared Inputs
@@ -254,7 +254,7 @@ does not abort an MXAccess COM call that is already executing on the worker STA.
 
 ## Related Documentation
 
-- [Client Proto Generation](./client-proto-generation.md)
-- [Client Libraries Detailed Design](./client-libraries-design.md)
+- [Client Proto Generation](./ClientProtoGeneration.md)
+- [Client Libraries Detailed Design](./ClientLibrariesDesign.md)
 - [Client Behavior Fixtures](./ClientBehaviorFixtures.md)
-- [Toolchain Links](./toolchain-links.md)
+- [Toolchain Links](./ToolchainLinks.md)