B21: Reject malformed log topics

[KillariDev]

What changed

• validate every RPC log topic as exactly 32 bytes
• apply the check to direct log queries and receipt-embedded logs
• preserve valid mixed-case topics with lowercase normalization

Why

The shared client previously treated topics as arbitrary byte data, allowing malformed provider values such as 0x12 to enter decoded and raw log flows even though EVM log topics are always bytes32.

Validation

• bun test shared/ts/ethereum.test.ts --timeout=600000 (34 pass)
• bun run tsc
• clean full suite rerun (3,253 pass, 16 skip)
• isolated rerun of one transient unchanged browser smoke timeout (1 pass)
• bun run format:check
• bun run check:changed
• bun run knip
• git diff --check
• final review: 100/100