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>

clients/rust/README.md

@@ -4,7 +4,7 @@ The Rust client workspace contains the MXAccess Gateway client library, a
 test CLI, and tests for generated contract wiring plus wrapper behavior. The
 library uses
 the shared protobuf inputs documented in
-`../../docs/client-proto-generation.md` so the Rust bindings compile against
+`../../docs/ClientProtoGeneration.md` so the Rust bindings compile against
 the same public gateway and worker contracts as the server.
 
 ## Layout
@@ -36,7 +36,7 @@ cargo clippy --workspace --all-targets -- -D warnings
 ```
 
 The build script uses `protoc` from `PATH` or the Windows path recorded in
-`../../docs/toolchain-links.md`.
+`../../docs/ToolchainLinks.md`.
 
 ## Packaging
 
@@ -184,6 +184,6 @@ cargo run -p mxgw-cli -- smoke --endpoint $env:MXGATEWAY_ENDPOINT --plaintext --
 ## Related Documentation
 
 - [Client Packaging](../../docs/ClientPackaging.md)
-- [Client Proto Generation](../../docs/client-proto-generation.md)
-- [Rust Client Detailed Design](../../docs/clients-rust-design.md)
+- [Client Proto Generation](../../docs/ClientProtoGeneration.md)
+- [Rust Client Detailed Design](./RustClientDesign.md)
 - [Rust Style Guide](../../docs/style-guides/RustStyleGuide.md)