fix(identity): Sweep stale merge-marker artifacts after KycTier cleanup (#553)

[nanaf6203-bit]

Verify no leftover <<<<<<</=======/>>>>>>> markers remain in contracts/identity/lib.rs after PR #553. Add a regex sweep in CI to prevent recurrence.

[solidsole]

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[ummarig]

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Please assign this issue to me my eta is 3 hours

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