Matrix: insert Form C + update + delete coverage

34 new tests covering:
- Form C bare-value-list (happy path + Form-A-recovery + type-unaware grammar limitation per handoff §2.2)
- update with WHERE (column-narrowing invariant per handoff §1 bug E1; typed-slot prose for assignments and where filters)
- update --all-rows (filter-clause requirement per ADR-0014)
- delete with WHERE (column-narrowing; typed-slot prose for where filters)
- delete --all-rows

859 baseline -> 931 passing. No bugs surfaced — the data-mutation
command family was already well-shaped post-Phase-D.

tests/typing_surface/update_all_rows.rs

@@ -1 +1,54 @@
-//! Submodule stub — populated in subsequent tasks.
+//! Matrix coverage for `update T set col=val --all-rows`
+//! (ADR-0014 opt-in for unfiltered updates).
+
+use crate::typing_surface::*;
+use rdbms_playground::input_render::InputState;
+
+#[test]
+fn before_all_rows_flag_is_incomplete() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='x' ",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    // Both `where` and `--all-rows` are valid continuations.
+    assert_candidate_present(&a, &["--all-rows"]);
+    crate::snap!("before_all_rows", a);
+}
+
+#[test]
+fn complete_update_all_rows_parses() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='new@b.c' --all-rows",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::Valid));
+    assert_eq!(a.parse_result.as_deref(), Ok("Update"));
+    crate::snap!("complete_all_rows", a);
+}
+
+#[test]
+fn update_without_filter_clause_is_incomplete() {
+    // Per ADR-0014, update requires WHERE or --all-rows.
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='new@b.c'",
+        &schema,
+    );
+    assert!(matches!(a.state, InputState::IncompleteAtEof));
+    crate::snap!("no_filter_clause", a);
+}
+
+#[test]
+fn update_partial_flag_name_is_incomplete() {
+    let schema = schema_serial_pk();
+    let a = assess_at_end(
+        "update Customers set Email='x' --all",
+        &schema,
+    );
+    // Partial flag still in progress.
+    assert!(!matches!(a.state, InputState::Valid));
+    crate::snap!("partial_flag", a);
+}