chore: gitignore private .claude/ working paths (#356)

Private Claude Code working files (plans, transcripts, todos, local settings)
were not ignored, so a `.claude/plans/` doc slipped into a PR. Ignore the
per-user/agent scratch paths while keeping the intentionally-tracked shared
team config (.claude/settings.json, hooks/, skills/).

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

Author: prasanna-anchorage

.gitignore

@@ -2,3 +2,14 @@
 out
 docs/superpowers/
 .surfpool/
+
+# Claude Code private/working files. The shared team config under .claude/
+# (settings.json, hooks/, skills/) IS tracked and intentionally not matched
+# here; everything below is per-user/agent scratch that must never be committed
+# (a plan doc slipped into a PR once -- see the trust-model PR).
+.claude/plans/
+.claude/projects/
+.claude/todos/
+.claude/shell-snapshots/
+.claude/statsig/
+.claude/settings.local.json