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/mod.rs

@@ -22,25 +22,25 @@ use rdbms_playground::input_render::{
 };
 use rdbms_playground::mode::Mode;
 
+pub mod add_relationship;
+pub mod app_commands;
+pub mod candidate_ordering;
+pub mod constraints;
+pub mod create_m2n;
+pub mod create_table;
+pub mod delete_all_rows;
+pub mod delete_with_where;
+pub mod drop_column;
+pub mod drop_relationship;
+pub mod explain;
+pub mod index_ops;
 pub mod insert_form_a;
 pub mod insert_form_b;
 pub mod insert_form_c;
-pub mod update_with_where;
-pub mod update_all_rows;
-pub mod delete_with_where;
-pub mod where_expression;
-pub mod delete_all_rows;
-pub mod explain;
-pub mod create_table;
-pub mod drop_column;
-pub mod drop_relationship;
-pub mod add_relationship;
-pub mod create_m2n;
-pub mod index_ops;
-pub mod constraints;
 pub mod rename_change_column;
-pub mod app_commands;
-pub mod candidate_ordering;
+pub mod update_all_rows;
+pub mod update_with_where;
+pub mod where_expression;
 
 // =========================================================
 // Canonical schema shapes (handoff §1 — CANONICAL_SCHEMA_SHAPES)
@@ -81,10 +81,7 @@ pub fn schema_serial_pk() -> SchemaCache {
 /// Exercises the no-auto-gen path: Form A and Form B both
 /// require values for every column.
 pub fn schema_text_pk() -> SchemaCache {
-    build_schema(&[(
-        "Items",
-        &[("Code", Type::Text), ("Title", Type::Text)],
-    )])
+    build_schema(&[("Items", &[("Code", Type::Text), ("Title", Type::Text)])])
 }
 
 /// Two tables sharing no column names.
@@ -96,10 +93,7 @@ pub fn schema_text_pk() -> SchemaCache {
 /// the other table.
 pub fn schema_multi_table() -> SchemaCache {
     build_schema(&[
-        (
-            "Customers",
-            &[("id", Type::Serial), ("Name", Type::Text)],
-        ),
+        ("Customers", &[("id", Type::Serial), ("Name", Type::Text)]),
         (
             "Orders",
             &[
@@ -436,10 +430,7 @@ fn smoke_assess_at_end_returns_each_field() {
 #[test]
 fn smoke_assess_parse_label_round_trips() {
     let schema = schema_serial_pk();
-    let a = assess_at_end(
-        "insert into Customers values ('Alice', 'a@b.c')",
-        &schema,
-    );
+    let a = assess_at_end("insert into Customers values ('Alice', 'a@b.c')", &schema);
     assert_eq!(a.parse_result.as_deref(), Ok("Insert"));
     assert!(matches!(a.state, InputState::Valid));
 }
@@ -462,7 +453,11 @@ fn seed_completion_and_validity() {
     // Validity (ADR-0027): a known table seeds clean; an unknown one is
     // flagged (same table slot as update/delete/show data).
     let ok = assess_at_end("seed Customers 5", &schema);
-    assert!(matches!(ok.state, InputState::Valid), "known table: {:?}", ok.state);
+    assert!(
+        matches!(ok.state, InputState::Valid),
+        "known table: {:?}",
+        ok.state
+    );
     // seed's unknown-table behaviour must match its closest sibling
     // `show data` (same table-only slot), whatever that is.
     let seed_ghost = assess_at_end("seed Ghost 5", &schema).state;