docs: add Claude formatting instructions

CLAUDE.md

@@ -130,3 +130,49 @@ Each component directory contains a `summary.md` file documenting:
 - `docs/handover/` - Comprehensive architecture documentation
 - `ARCHITECTURE.md` - Migration guide for old vs new style
 - Component-specific `summary.md` files throughout the codebase
+
+## Claude Development Guidelines
+
+This section contains specific instructions for Claude when working on this
+project.
+
+### Formatting Commands
+
+After making any code modifications, run the appropriate formatting commands:
+
+#### Markdown Files
+
+- **Format**: Run `make format-md` after modifying any markdown files
+- **Check**: Run `make check-md` to verify markdown files are formatted
+  correctly
+
+#### Rust and TOML Files
+
+- **Format**: Run `make format` after modifying any Rust (.rs) or TOML (.toml)
+  files
+- **Check**: Run `make check-format` to verify Rust and TOML files are formatted
+  correctly
+
+### Commit Guidelines
+
+**NEVER** add Claude as a co-author in commit messages. Do not include:
+
+- `Co-Authored-By: Claude <[email protected]>`
+- Any other co-author attribution for Claude
+
+**NEVER** use emojis in commit messages.
+
+**Always** wrap commit message titles at 80 characters and body text at 80
+characters.
+
+Always verify commit messages before committing and remove any co-author lines
+referencing Claude.
+
+### Development Workflow
+
+1. Make your code changes
+2. Run the appropriate formatting command based on file types modified
+3. Verify formatting with check commands if needed
+4. **Verify commit message does not include Claude as co-author**
+5. **Verify commit message contains no emojis and follows 80-character wrap**
+6. Proceed with testing or committing changes