feat: ADR-0036 Phase 1 — validate advanced-mode INSERT literals + show the value

Capture literal VALUES at parse onto Command::SqlInsert (no grammar change,
no reparse); validate them against column types before the still-verbatim
insert (reusing impl_value_for for DSL-parity wording); read them in the
error enricher so a constraint error names the real value. Execution,
auto-fill, and command identity unchanged. Adds run_sql_insert_with_literals
(runtime path); run_sql_insert stays the no-capture raw entry.

Proven: malformed date 2025/01/15 now refused in advanced-mode SQL; replayed
UNIQUE shows the real value. Tests +3 (expression runs, multi-row, natural
order) + 2 flipped/strengthened. 1930 pass / 0 fail / 0 skip; clippy clean.

src/dsl/command.rs

@@ -422,6 +422,15 @@ pub enum Command {
         /// `DataResult` when true; otherwise it surfaces the
         /// affected-row count (+ auto-show) as before.
         returning: bool,
+        /// Captured literal values per `VALUES` row, per position
+        /// (ADR-0036 Phase 1). `Some(v)` for a bare literal (incl. a
+        /// signed number); `None` for an expression position (nothing
+        /// static to validate). Empty when the row source is a
+        /// `SELECT`/`WITH` query. The worker validates these against the
+        /// column types before the (still verbatim) insert; the error
+        /// enricher reads them to show the offending value. Execution
+        /// itself is unchanged — these are *not* bound.
+        literal_rows: Vec<Vec<Option<Value>>>,
     },
     /// A SQL `UPDATE` validated by the walker (ADR-0033 §2,
     /// advanced mode). Grammar-as-text: the worker executes `sql`