fix(#974): add 39 example-db tests and 31 paper entries for reduction rules

[zazabap]

Summary

• Adds 39 test_find_rule_example_* lookup tests in src/unit_tests/example_db.rs covering all cross-problem reductions from PRs feat: add 8 Tier 1a reduction rules (#770) #777, feat: add 12 Tier 1b high-confidence reduction rules (#770) #779, feat: add 11 Tier 1a + 1b medium-confidence reduction rules (#770) #804, feat: add 10 reduction rules (#770) #972
• Adds 31 #reduction-rule(...) entries in docs/paper/reductions.typ — 30 cross-problem reductions + 1 ILP → ILP variant reduction
• ILP i32→bool is a same-name variant edge excluded from the coverage test by design; its 10 existing unit tests provide thorough coverage

Test plan

• make check passes (fmt + clippy + test)
• cargo test --lib --features example-db test_find_rule_example_ — all 44 rule lookup tests pass
• typst compile docs/paper/reductions.typ — compiles with no errors
• canonical_rule_examples_cover_exactly_authored_direct_reductions — coverage test passes

Closes #974

🤖 Generated with Claude Code — Institute of Science Tokyo

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.16%. Comparing base (c57a131) to head (15052ea).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #997      +/-   ##
==========================================
+ Coverage   98.15%   98.16%   +0.01%     
==========================================
  Files         896      896              
  Lines       91150    91715     +565     
==========================================
+ Hits        89472    90036     +564     
- Misses       1678     1679       +1     

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[GiggleLiu]

Wield, did you use the paper writing skills? why data are hard coded in examples? Example data in manual should be loaded from json, and json is dumped from example_db.

[zazabap]

You're right — the entries weren't generated with the paper writing skill. Fixing now: upgrading all 30 cross-problem entries to use load-example() with data-driven examples. Will push shortly.