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.

src/dsl/grammar/mod.rs

@@ -27,9 +27,9 @@ pub mod data;
 pub mod ddl;
 pub mod expr;
 pub mod shared;
-pub mod sql_expr;
 pub mod sql_create_table;
 pub mod sql_delete;
+pub mod sql_expr;
 pub mod sql_insert;
 pub mod sql_select;
 pub mod sql_update;
@@ -328,9 +328,7 @@ pub enum Node {
     /// A number literal. The optional `validator` runs against
     /// the matched text (used by Phase D value slots to enforce
     /// per-type integer/decimal rules).
-    NumberLit {
-        validator: Option<NumberValidator>,
-    },
+    NumberLit { validator: Option<NumberValidator> },
     /// A literal byte sequence at this position — matches
     /// bytes verbatim (whitespace-skipped) with a lookahead so
     /// `1` doesn't half-match `12` and `n` doesn't half-match
@@ -701,7 +699,11 @@ fn selected_nodes_for_input_in_mode(
                 .filter(|(_, _, c)| *c == CommandCategory::Simple)
                 .collect()
         };
-    if selected.is_empty() { candidates } else { selected }
+    if selected.is_empty() {
+        candidates
+    } else {
+        selected
+    }
 }
 
 /// The single usage template most relevant to `source`, when
@@ -724,10 +726,7 @@ pub fn usage_key_for_input(source: &str) -> Option<&'static str> {
 /// disambiguates the single most-relevant usage key from the
 /// mode-selected key set.
 #[must_use]
-pub fn usage_key_for_input_in_mode(
-    source: &str,
-    mode: crate::mode::Mode,
-) -> Option<&'static str> {
+pub fn usage_key_for_input_in_mode(source: &str, mode: crate::mode::Mode) -> Option<&'static str> {
     let (_entry, keys) = usage_keys_for_input_in_mode(source, mode)?;
     pick_form_key(source, &keys)
 }
@@ -755,7 +754,10 @@ fn pick_form_key<'a>(source: &str, keys: &[&'a str]) -> Option<&'a str> {
     }
     // The `create m:n relationship` form (ADR-0045) opens with `m:n`
     // — a letter, so the digit branch misses it; its key ends `…m2n`.
-    if source[after..].get(..3).is_some_and(|s| s.eq_ignore_ascii_case("m:n")) {
+    if source[after..]
+        .get(..3)
+        .is_some_and(|s| s.eq_ignore_ascii_case("m:n"))
+    {
         return keys.iter().copied().find(|k| k.ends_with("m2n"));
     }
     // Otherwise the form word is an identifier — `column`, `index`,
@@ -770,8 +772,7 @@ fn pick_form_key<'a>(source: &str, keys: &[&'a str]) -> Option<&'a str> {
 /// which read the same data through the legacy `usage::REGISTRY`.
 #[must_use]
 pub fn entry_words_alphabetised() -> Vec<&'static str> {
-    let mut words: Vec<&'static str> =
-        REGISTRY.iter().map(|(c, _)| c.entry.primary).collect();
+    let mut words: Vec<&'static str> = REGISTRY.iter().map(|(c, _)| c.entry.primary).collect();
     words.sort_unstable();
     words.dedup();
     words
@@ -905,9 +906,7 @@ pub fn command_for_entry_word(word: &str) -> Option<(usize, &'static CommandNode
 /// returns its `Simple` DSL node and `Advanced` SQL node. The
 /// dispatcher picks among them by the active input mode.
 #[must_use]
-pub fn commands_for_entry_word(
-    word: &str,
-) -> Vec<(usize, &'static CommandNode, CommandCategory)> {
+pub fn commands_for_entry_word(word: &str) -> Vec<(usize, &'static CommandNode, CommandCategory)> {
     REGISTRY
         .iter()
         .enumerate()
@@ -1010,7 +1009,10 @@ mod hint_key_tests {
         ];
         for c in classes {
             let key = format!("hint.err.{c}.what");
-            assert!(cat.get(&key).is_some(), "missing tier-3 error block `{key}`");
+            assert!(
+                cat.get(&key).is_some(),
+                "missing tier-3 error block `{key}`"
+            );
         }
     }
 
@@ -1098,10 +1100,7 @@ mod usage_key_tests {
         let cases = [
             ("add column to T: c (int)", "parse.usage.add_column"),
             ("add index on T (c)", "parse.usage.add_index"),
-            (
-                "add constraint unique to T.c",
-                "parse.usage.add_constraint",
-            ),
+            ("add constraint unique to T.c", "parse.usage.add_constraint"),
             (
                 "drop constraint check from T.c",
                 "parse.usage.drop_constraint",
@@ -1118,10 +1117,7 @@ mod usage_key_tests {
             ("drop table T", "parse.usage.drop_table"),
             ("drop column from table T: c", "parse.usage.drop_column"),
             ("drop index i", "parse.usage.drop_index"),
-            (
-                "drop relationship r",
-                "parse.usage.drop_relationship",
-            ),
+            ("drop relationship r", "parse.usage.drop_relationship"),
             ("show data T", "parse.usage.show_data"),
             ("show table T", "parse.usage.show_table"),
             // `create` is multi-form (table vs m:n, ADR-0045): each typed