feat: convex claim

[jpsains]

Note

Medium Risk
Updates heuristic topic matching for a reward-claim event signature, which could affect categorization of other protocols emitting the same RewardPaid topic if not sufficiently scoped.

Overview
Adds recognition of Convex reward claims by mapping the staked CVX reward pool address and the RewardPaid log topic to a CLAIM action, producing CONVEX_CLAIM metadata.

Extends the test suite with a new Ethereum mainnet fixture/txHash and updates snapshots/expected V6 readable label (Claimed 97.2854 cvxCRV) to validate the new categorization.

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