security: open redirect / unsafe share URL risk in share buttons

[nanaf6203-bit]

Summary

The Property share button uses navigator.share + an unvalidated URL builder; the MortgageCalculator share HTML also serialises raw values into a URL.

Affected area

• src/components/property/ShareButton.tsx
• src/components/MortgageCalculator.tsx

Steps to reproduce / impact

A property title with newlines or shell metacharacters can break the share dialog or be misinterpreted downstream.

Expected behaviour

URL-encode all parameters, sanitise display strings to a constrained character set, validate the returned URL via URL constructor, and warn on cross-origin links.

Acceptance criteria

• Helper centralising share-URL construction.
• Tests with adversarial inputs.

[KingDavid9999]

@KingDavid9999 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I'd very much appreciate the opportunity to work on this issue.
Having reviewed the acceptance criteria, I'm confident that I'd be able to have a PR up shortly after being assigned.
Kindly assign this issue to me.
Thank you!

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[daniel007-ai]

@daniel007-ai has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

sir i can work on this issue sir

ℹ️ Repo Maintainers: To accept this application, review their application or assign @daniel007-ai to this issue.

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Congratulations, @daniel007-ai! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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[drips-wave]

This issue has been completed by @daniel007-ai as part of the Stellar Wave Program's 6th Wave 🥳

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