fix(ethereum2): receipt-local event indices and legacy proof compatibility

[fengjy73]

Problem

Ethereum JSON-RPC logIndex is block-global, while the receipt proof authenticates one transaction's logs array. The collector stored the global value and HCDVS indexed the receipt with it, rejecting valid AM messages in later transactions of a block. The filter collector also expanded every matched log into every AM event in its receipt, duplicating/mixing messages.

Fix

• Both collector modes use one receipt-local locator and emit one message per selected AM event.
• New ledgers explicitly record receiptLogIndex and a consistent local logIndex while retaining the original RPC log metadata.
• HCDVS authenticates the original receipt proof against the trusted consensus root, checks transaction index, trusted AM address, full topics/data and decoded message.
• Explicit local indices are strict: invalid positions never fall back. Legacy messages require a unique full-event match inside the proven receipt and consistent index metadata; ambiguous events fail closed.
• No proof bypass, RPC fallback, source re-submission, stored-UCP rewriting, or contract changes.

Based on upstream main ec89a28; preserves the existing consensus/light-client fixes. This PR contains only generic Ethereum2 changes, not downstream Ethereum3/regulatory code.

Tests

• Java 21 targeted tests: 23 passed, including both actual collector methods with mocked RPC, multi-transaction blocks/multiple AM events, real receipt/consensus fixtures, legacy compatibility, explicit-index failures, ambiguity, malformed metadata, and proof/root/message tampering.
• Java 21 package build passed. Existing generated ABI classes were prepared before compilation; no ABI or contract source changes.

Downstream deployment evidence

The equivalent downstream fix (ICT PR #7) was deployed to the Plugin Server and all four PTC nodes. This is not a claim that the upstream branch artifact was installed.

• Original ordinary burst: 96/96 completed, including 93 previously blocked messages. All 96 stored raw_message fingerprints unchanged, target payload once, PTC100%.
• Existing 96 Mychain regulated +32 cross-plugin competition messages revalidated successfully; Dioxide reverse and Ethereum→FISCO SDP V1/V2/V3 samples remained successful.
• Four newly collected same-block messages (2 ordinary +2 regulated) completed; second-transaction global/local pairs were 2/0 and 4/1. The independent FISCO SDK confirmed both new regulated target receipts succeeded with the exact unwrapped payload once.
• Final Dioxide coordination journal: 229 unique ISNs, all FINALIZED. Existing finality policy and contracts unchanged.

Runbook: acb-sdk/pluginset/ethereum2/RECEIPT_LOG_INDEX.md. Collector and every committee member's HCDVS should be deployed together with component-specific rollback backups. Unexecuted Mychain ordinary / native Dioxide SDP V2/V3 combinations are not counted as passed.