Add guardrails for example-only documentation data

[ChristianPavilonis]

Summary

• Add CLAUDE.md guardrails requiring comments, tests, docs, examples, and similar materials to use only example or fictional information.
• Expand the existing commit restrictions to cover potentially sensitive real-world information in non-runtime artifacts and configuration files.

Changes

File	Change
CLAUDE.md	Adds example-only guidance for comments, tests, docs, and examples.
CLAUDE.md	Expands the “What NOT to Do” guidance to prohibit committing potentially sensitive real-world information.

Closes

Closes #703

Test plan

• cargo test --workspace
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/js/lib && npx vitest run
• JS format: cd crates/js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --package trusted-server-adapter-fastly --release --target wasm32-wasip1
• Manual testing via fastly compute serve
• Other: Docs-only change; reviewed CLAUDE.md diff.

Checklist

• Changes follow CLAUDE.md conventions
• No unwrap() in production code — use expect("should ...")
• Uses tracing macros (not println!)
• New code has tests
• No secrets or credentials committed