bug: suggest-a-place dialog accepts any string as a Google Maps link and loses input when the popup is blocked

[shauryagangrade]

Problem

Two issues in src/components/map/suggest-place-dialog.tsx:85-99:

1. No URL validation — isValid accepts any non-empty string as the "Google Maps link", so typos like google maps com/place/x sail through into the pre-filled GitHub issue.
2. Popup-blocked data loss — window.open(url, "_blank") returns null when the browser blocks the popup, but the code doesn't check the result: the dialog still closes and everything the user typed is gone with zero feedback.

Suggested fix

• Validate with URL constructor + require a maps.google. / goo.gl/maps host (or at least any valid http(s) URL)
• If window.open returns null: keep the dialog open and show a toast + clickable fallback link ("Pop-up blocked — open GitHub here"), so submissions survive

Acceptance criteria

• Invalid URLs are rejected inline
• Blocked popups never destroy entered data