style: format the whole tree with cargo fmt (stock defaults, #35)

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.

tests/typing_surface/where_expression.rs

@@ -95,10 +95,7 @@ fn show_data_after_where_predicate_offers_limit() {
 #[test]
 fn complete_show_data_with_where_and_limit_parses() {
     let schema = schema_serial_pk();
-    let a = assess_at_end(
-        "show data Customers where id=1 limit 10",
-        &schema,
-    );
+    let a = assess_at_end("show data Customers where id=1 limit 10", &schema);
     assert!(matches!(a.state, InputState::Valid));
     assert_eq!(a.parse_result.as_deref(), Ok("ShowData"));
     crate::snap!("complete_show_where_limit", a);