chore: stop tracking .claude/settings.local.json (personal local config) (#342)

It's Claude Code's per-user permission allowlist — auto-modified on every
permission approval, so it kept dirtying the working tree and risked
leaking personal settings into the public repo. Local file is preserved.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -8,3 +8,6 @@ build/
 .env
 .agent-reach/
 *.log
+
+# Claude Code personal permission settings — local only, never commit
+.claude/settings.local.json