One-time, mechanical reformat — no functional changes. The tree was not
rustfmt-clean (~1800 hunks across ~100 files); this brings it to stock
`cargo fmt` defaults so a `cargo fmt --check` CI gate can follow.
Behaviour-preserving: 2509 pass / 0 fail / 1 ignored (unchanged baseline),
clippy clean. A .git-blame-ignore-revs entry follows so `git blame`
skips this commit.
13 matrix cells for the `explain` prefix across all three
wrapped commands — `explain show data` / `explain update` /
`explain delete` — covering each typing position (after the
prefix, the inner entry word, the table, the filter clause)
plus the three complete forms. The cells confirm `explain`
plugs into the inner query grammars cleanly: candidates, hints
and column scoping match the standalone commands, and the
complete forms parse as `Command::Explain`.
Also adds a worker test pinning the display SQL's `<>`
rendering of inequality (ADR-0028 §3).
Matrix: 161 -> 174 cells. 1172 tests pass; clippy clean.