ref(explore): Move updateNullableLocation to utils/url/

[ryan953]

Summary

• Moves updateNullableLocation from views/explore/queryParams/location.ts to utils/url/updateNullableLocation.ts
• Updates all 5 import sites to point to the new location
• Deletes the old file (git detects as rename)

Test plan

• All pre-commit hooks pass
• No remaining imports from the old path

[github-actions]

📊 Type Coverage Diff

✅ No new type safety issues introduced. Coverage: 93.50%