bug: replace Math.random() with CSPRNG for transaction IDs and hashes

[nanaf6203-bit]

Summary

Non-cryptographic Math.random() is used to generate transaction hashes, transaction IDs, audit IDs, and alert IDs in several places where unguessable IDs are required.

Affected area

• tests/e2e/property-purchase-flow.spec.ts (Math.random().toString(16).substring(2, 66) for tx hash)
• src/components/dashboard/PropertyCard.tsx (mockTxHash)
• src/components/dashboard/DataRefreshWrapper.tsx (random failure branching)
• src/hooks/useRewardDistribution.ts (mockTxHash)
• src/lib/batchTransaction.ts (blockNumber, success ratio, fake tx hash)
• src/lib/secondaryMarketService.ts (tx hash and IDs)
• src/lib/notificationService.ts, src/lib/kyc.ts, src/utils/structuredLogger.ts, src/utils/audit/transactionAudit.ts, src/utils/errorMonitoringService.ts, src/utils/security/auditLogger.ts, src/utils/security/transactionMonitor.ts

Steps to reproduce / impact

Math.random is not cryptographically secure. An attacker who can guess the seed or run the same PRNG state can collide IDs, impersonate transactions in tests, or defeat rate-limited ID-based logic. The same PRNG is also used to fake transaction hashes that downstream code might treat as canonical.

Expected behaviour

Use crypto.randomUUID() (already used in some places, e.g. src/utils/security/transactionSecurity.ts) or crypto.getRandomValues for all transaction-related IDs and hashes.

Acceptance criteria

• Replace every Math.random() call involved in generating transaction IDs, hashes, audit IDs, and alert IDs with a CSPRNG.
• Convert every Math.random().toString(...).substr(2, N) chain to a length-normalised hex helper backed by crypto.getRandomValues.
• Add unit tests proving randomness is not trivial to predict (length, hex-only, unique).

[OluRemiFour]

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

I've reviewed the issue and understand the requirements. I'd love to work on this and submit a clean PR that meets the acceptance criteria.

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[JamesEjembi]

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

i would like to work on this issue

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