Rust hygiene: collapse compare_archive.rs into compare.rs

[willwashburn]

Context

crates/relayburn-sdk/src/analyze/compare_archive.rs is 753 lines that documents itself out of existence. Its own doc says (paraphrasing) "per #259's redesign, the Rust ledger is already SQLite-only, so this port is a thin shell." The actual logic is a 5-line wrapper around Ledger::query_turns + build_compare_table.

The other ~750 lines are fixture and helper boilerplate to test what is fundamentally a one-liner.

Proposed fix

1. Move compare_from_archive (the one functional helper) into crates/relayburn-sdk/src/analyze/compare.rs as a small fn.
2. Re-target the test cases that actually exercise distinct compare logic into compare.rs's test module; drop the duplicate fixtures.
3. Delete crates/relayburn-sdk/src/analyze/compare_archive.rs.
4. Update crates/relayburn-sdk/src/analyze.rs to keep the public compare_from_archive re-export pointing at the new location — that keeps the SDK surface stable.

Verify the conformance gate (deep-equal vs TS) keeps passing on the compare verb.

References

• crates/relayburn-sdk/src/analyze/compare_archive.rs
• crates/relayburn-sdk/src/analyze/compare.rs
• crates/relayburn-sdk/src/analyze.rs:54 (re-export site)
• Analyze review notes from the May 2026 Rust review.