security: rate-limit phishing detection lookups

[nanaf6203-bit]

Summary

Phishing detection in src/utils/security/phishingProtection.ts runs synchronously per navigation. Calling PhishingProtection.detectPhishing on every render or every navigation event without debouncing/rate-limit burns CPU and could be abused via DOM-style events.

Affected area

src/utils/security/phishingProtection.ts

Steps to reproduce / impact

Excessive clones / iframes force N domain checks per second.

Expected behaviour

Memoise per window.location.origin for the lifetime of the page, and rate-limit background reporting.

Acceptance criteria

• Memoisation in place.
• Add a benchmark test confirming constant-time verification regardless of count.

[sandrawillow001-afk]

@sandrawillow001-afk has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

hello sir i can wok on this issue sir

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This issue has been completed by @sandrawillow001-afk as part of the Stellar Wave Program's 6th Wave 🥳

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