Before this commit, `cargo test --doc --manifest-path src-tauri/Cargo.toml`
failed: the indented formula at return_calculator.rs:12-13 was parsed by
rustdoc as a Rust code block and the pseudo-math (`R = ... sum(CF_i)`)
did not compile. Pre-existing since commit 531624b.
Wrapping the formula in an explicit `\`\`\`text` fence tells rustdoc to
render but not compile-test the block. `cargo test --doc` now passes
(0 doctests, no failures).
Also adds the consolidated #187 entry to CHANGELOG.md and CHANGELOG.fr.md
under Fixed/Corrigé summarizing all six fixes (S1, S2, S3, S4, S5, S7) —
S6 already factorized, S8 deferred to backlog, S9 obsolete.
Suggestion S7 from worker note on #176 (#187).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>