Add perf testing aliases, knowledgebase sync, and ignore .claude dir

- Add yalp:perf and yalp:perf:stop aliases for YALP Core perf testing
- Add sync-knowledgebases function and kb-sync alias
- Add .claude/ to .gitignore

.gitignore

@@ -1,2 +1,3 @@
 # Local Natera config with account IDs, IPs, and internal paths (never commit)
 zshrc-natera.private
+.claude/