fix(fk): inline FK referencing a compound PK points at the table-level form

ADR-0043 D4 residual: an inline column-level FK (`<col> REFERENCES P(a,b)`)
is single-column by construction, so referencing a parent's compound PK
gave the generic arity error ("1 foreign-key column(s) on the child side,
but `P`'s key has 2..."). It now points the user at the table-level form:
"an inline column reference can only name one column ... Use the table-level
form instead: FOREIGN KEY (<columns>) REFERENCES P (a, b)".

- Adds `inline: bool` to SqlForeignKey, set by the grammar's single shared
  builder consume_fk_reference (true for the inline path, false for the
  table-level and ALTER paths).
- resolve_fk_parent_columns takes `inline` and tailors the arity-mismatch
  message when an inline FK meets a compound key.

Tests: parse-layer (inline=true / table-level=false) + end-to-end worker
refusal wording. 2209 pass / 0 fail / 1 ignored. Clippy clean.

tests/it/compound_fk.rs

@@ -137,6 +137,7 @@ fn sql_create_table_compound_fk_executes_and_enforces() {
                 parent_columns: Some(vec!["country".to_string(), "code".to_string()]),
                 on_delete: ReferentialAction::NoAction,
                 on_update: ReferentialAction::NoAction,
+                inline: false,
             }],
             false,
             None,
@@ -363,6 +364,65 @@ fn compound_fk_arity_mismatch_is_refused() {
     });
 }
 
+#[test]
+fn inline_fk_referencing_compound_pk_points_at_table_level_form() {
+    // ADR-0043 D4 residual: an *inline* single-column FK cannot express a
+    // multi-column reference, so referencing a parent's compound PK must
+    // refuse with a pointer to the table-level `FOREIGN KEY (...)` form —
+    // not the generic arity message. The grammar marks the FK `inline`.
+    let (_p, db, _dir) = open_project_db();
+    let rt = rt();
+    rt.block_on(async {
+        db.create_table(
+            "Region".to_string(),
+            vec![
+                ColumnSpec::new("country", Type::Int),
+                ColumnSpec::new("code", Type::Int),
+            ],
+            vec!["country".to_string(), "code".to_string()],
+            None,
+        )
+        .await
+        .expect("create Region");
+
+        // Parse the inline form so the `inline` flag is set by the grammar.
+        let cmd = parse_command(
+            "create table City (country int references Region(country, code))",
+        )
+        .expect("parses");
+        let Command::SqlCreateTable {
+            name,
+            columns,
+            primary_key,
+            unique_constraints,
+            check_constraints,
+            foreign_keys,
+            if_not_exists,
+        } = cmd
+        else {
+            panic!("expected SqlCreateTable");
+        };
+        let err = db
+            .sql_create_table(
+                name,
+                columns,
+                primary_key,
+                unique_constraints,
+                check_constraints,
+                foreign_keys,
+                if_not_exists,
+                None,
+            )
+            .await
+            .expect_err("inline FK referencing a compound PK must be refused");
+        let msg = format!("{err}");
+        assert!(
+            msg.contains("FOREIGN KEY"),
+            "expected a pointer to the table-level `FOREIGN KEY (...)` form, got: {msg}"
+        );
+    });
+}
+
 #[test]
 fn compound_fk_type_mismatch_per_pair_is_refused() {
     let (_p, db, _dir) = open_project_db();

tests/it/sql_create_table.rs

@@ -839,6 +839,7 @@ fn fk(child_column: &str, parent_table: &str, parent_column: Option<&str>) -> Sq
         parent_columns: parent_column.map(|c| vec![c.to_string()]),
         on_delete: ReferentialAction::NoAction,
         on_update: ReferentialAction::NoAction,
+        inline: false,
     }
 }
 

tests/it/sql_drop_table.rs

@@ -109,6 +109,7 @@ fn dropping_a_referenced_parent_is_refused() {
             parent_columns: Some(vec!["id".to_string()]),
             on_delete: rdbms_playground::dsl::ReferentialAction::NoAction,
             on_update: rdbms_playground::dsl::ReferentialAction::NoAction,
+            inline: true,
         }],
         false,
         Some("create table child (id serial primary key, pid int references parent(id))".to_string()),