feat(bitcoin): Increase OP_RETURN size limit to match Bitcoin Core v30

[EricGrill]

Summary

• Updates the OP_RETURN size limit from 80 bytes to 10,000 bytes to match Bitcoin Core v30's new default -datacarriersize
• Extends the pushDataLength() function in C++ to support OP_PUSHDATA2 for data larger than 255 bytes
• Removes the outdated 83-byte assertion that was blocking larger OP_RETURN scripts
• Adds comprehensive tests for various OP_RETURN data sizes (100, 255, 256, 1000, 10000 bytes)

Background

Bitcoin Core v30 increased the default -datacarriersize from 83 to 10,000 bytes. Transactions with OP_RETURN outputs larger than 80 bytes that are valid under Bitcoin Core 30 were failing to build in wallet-core due to hardcoded limits.

Changes

C++ Code:

• src/Bitcoin/Script.h: Updated MaxOpReturnLength from 80 to 10000
• src/Bitcoin/Script.cpp: Extended pushDataLength() to handle sizes > 255 bytes using OP_PUSHDATA2, removed 83-byte assertion

Rust Code:

• rust/frameworks/tw_utxo/src/transaction/standard_transaction/builder/output.rs: Updated OP_RETURN_DATA_LIMIT from 80 to 10000
• rust/frameworks/tw_utxo/src/script/standard_script/conditions.rs: Updated capacity hint in new_op_return()

Tests:

• tests/chains/Bitcoin/BitcoinScriptTests.cpp: Added tests for 100, 255, 256, 1000, and 10000 byte OP_RETURN data
• Rust tests added in output.rs for the same size ranges

Test plan

• Unit tests added for C++ buildOpReturnScript() with various data sizes
• Unit tests added for Rust OutputBuilder::op_return() with various data sizes
• Tests verify correct opcode selection (OP_PUSHBYTES_N, OP_PUSHDATA1, OP_PUSHDATA2)
• Tests verify rejection of data > 10000 bytes

Fixes #4548

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[sergei-boiko-trustwallet]

LGTM! But to be able to merge the PR, could you please add one test with a successfully broadcasted transaction on mainnet? You should generate a new private key, top up with ONLY required funds, and spend the entire balance before publishing the changes into the PR. That's needed to avoid funds loss.
Please add a comment like // Successfully broadcasted tx: https://...