Add CLAUDE.md with project-specific AI coding instructions

References AGENTS.md for project context and adds rules for:
- One sentence per line in markdown (per news/instructions.md)
- Including both getters and setters when listing API
- PR targeting conventions for fork-based workflow

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: vogella

CLAUDE.md

@@ -0,0 +1,11 @@
+@AGENTS.md
+
+# Additional Instructions for Claude Code
+
+## Markdown Formatting Rules
+- **One sentence per line.** Start each sentence on a new line and break long sentences into phrases on separate lines. This eases editing and produces cleaner diffs. See `news/instructions.md` for details.
+- When listing API methods, include both setters and getters if they exist in the source code.
+
+## Pull Requests
+- PRs for this repo target `eclipse-platform/www.eclipse.org-eclipse` (upstream), not the fork.
+- Use `gh pr create` with `--repo eclipse-platform/www.eclipse.org-eclipse --head vogella:<branch>` when pushing from a fork.