Add compression coverage for dynamic coin outputs

[0xjc65eth]

Summary

• add a regression test that builds a block with Coin, Change, and Variable outputs
• assert CompressionContext maps each output UTXO back to the expected tx pointer and output index

Why
Issue #3073 notes that Change and Variable outputs were previously missed when constructing the CompressionContext, and existing tests did not catch it. The implementation currently handles them; this test locks that behavior in.

Testing

• cargo test -p fuel-core-compression-service compression_context_indexes_coin_change_and_variable_outputs
• git diff --check -- crates/services/compression/src/temporal_registry.rs

Closes #3073.

[cursor]

PR Summary

Low Risk
Test-only change with no runtime or storage behavior modifications.

Overview
Adds a regression test in temporal_registry.rs that builds a block with Coin, Change, and Variable outputs and checks CompressionContext::create_from_block plus lookup return the expected tx_pointer and output_index for each UTXO.

No production logic changes in this diff—the test documents expected behavior for dynamic coin outputs (issue #3073) so future regressions in output indexing are caught.

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