Summary

• On startup, mergeBuiltInServices() reconciles the user's saved config with the latest defaultServices definitions
• Domains, IP ranges, and service names are always taken from the source code
• User's enabled/disabled preferences are preserved
• New services added in future releases appear automatically
• Config is only re-saved when changes are detected (no unnecessary writes)

How it works

1. After loading config.json, builds a lookup of saved services by id
2. Walks defaultServices in order (preserving source code ordering)
3. For each built-in service:
   • If it exists in saved config: takes enabled from saved, everything else from built-in
   • If it's new: adds it with defaults (enabled: false)
4. Appends any non-default services from saved config (forward compatibility)
5. Logs what changed and saves only if the merge produced differences

Test plan

• Fresh install: no config.json exists, app uses defaults — no merge needed
• Existing install with old OpenAI domains: after upgrade, OpenAI service should have all ~30 new domains while preserving enabled/disabled state
• Enable some services, upgrade, verify they remain enabled with updated domains
• New service added to source code appears in existing user's service list
• Config.json is only rewritten when actual changes are detected
• Export/import still works correctly

Closes #13