RPC: Prevent address balance overflow

[Tabakkui]

Problem

getaddressbalance accumulated the lifetime received value in signed CAmount (int64_t). Addresses with more than INT64_MAX received satoshis wrapped into a negative RPC result, as reported in #1227.

Approach

Accumulate positive address-index deltas in checked uint64_t storage for both the RVN and includeAssets paths. Return an RPC error rather than wrapping if the unsigned range is exceeded. Keep the current numeric JSON representation.

Test plan

• rpc_received_amount_overflow_test covers crossing the signed boundary, ignoring negative deltas for received, and rejecting unsigned overflow.
• received-overflow-helper: PASS from an UBSan-enabled helper smoke test.
• Legacy signed probe reproduces UBSan signed-overflow failure.
• git diff --cached --check passed.
• Full Ravencoin build/Boost test binary was not available in this Pi checkout; no full build was forced here.

Fixes #1227