Improve location-not-found error message with icon and field highlighting (#212)

[dikshajangra12918-oss]

Fixes #212

The "Location not found" error message was too generic and gave the user no guidance on what went wrong.

Changes:

• Replaced the generic message with a clearer one: "We couldn't find this location. Please check your city, state, or country spelling."
• Added a warning icon (⚠️) inside the error box for better visibility.
• The City input field now gets a red border when this error appears, so the user knows which field to check. The border clears automatically as soon as they start editing the field again.

Tested locally by leaving fields empty and by entering an invalid location combination — confirmed the message, icon, and red border all appear as expected.