docs update (#352)

I had an assistant go after the implementation and the docs here to get
things updated. @bkrabach please see workbench-app/docs/APP_DEV_GUIDE.md
in particular as I tried to incorporate principles from a side
conversation this week.

The CLAUDE.md file was produced by the new Claude Code app which appears
to use that as hints for repo code styles. Seemed reasonable and good.

CLAUDE.md

@@ -0,0 +1,41 @@
+# Semantic Workbench Developer Guidelines
+
+## Common Commands
+* Build/Install: `make install` (recursive for all subdirectories)
+* Format: `make format` (runs ruff formatter)
+* Lint: `make lint` (runs ruff linter)
+* Type-check: `make type-check` (runs pyright)
+* Test: `make test` (runs pytest)
+* Single test: `uv run pytest tests/test_file.py::test_function -v`
+* Frontend: `cd workbench-app && pnpm dev` (starts dev server)
+* Workbench service: `cd workbench-service && python -m semantic_workbench_service.start`
+
+## Code Style
+### Python
+* Indentation: 4 spaces
+* Line length: 120 characters
+* Imports: stdlib → third-party → local, alphabetized within groups
+* Naming: `snake_case` for functions/variables, `CamelCase` for classes, `UPPER_SNAKE_CASE` for constants
+* Types: Use type annotations consistently; prefer Union syntax (`str | None`) for Python 3.10+
+* Documentation: Triple-quote docstrings with param/return descriptions
+
+### C# (.NET)
+* Naming: `PascalCase` for classes/methods/properties, `camelCase` for parameters/local variables, `_camelCase` for private fields
+* Error handling: Use try/catch with specific exceptions, `ConfigureAwait(false)` with async
+* Documentation: XML comments for public APIs
+* Async: Use async/await consistently with cancellation tokens
+
+### TypeScript/React (Frontend)
+* Component files: Use PascalCase for component names and files (e.g., `MessageHeader.tsx`)
+* Hooks: Prefix with 'use' (e.g., `useConversationEvents.ts`)
+* CSS: Use Fluent UI styling with mergeStyle and useClasses pattern
+* State management: Redux with Redux Toolkit and RTK Query
+* Models: Define strong TypeScript interfaces/types
+
+## Tools
+* Python: Uses uv for environment/dependency management
+* Linting/Formatting: Ruff (Python), ESLint (TypeScript)
+* Type checking: Pyright (Python), TypeScript compiler
+* Testing: pytest (Python), React Testing Library (Frontend)
+* Frontend: React, Fluent UI v9, Fluent Copilot components
+* Package management: uv (Python), pnpm (Frontend)