Hint: pedagogical Form-A pointer at Form B's first value slot

Handoff-12 §2.2: Form B `insert into T values (…)` silently skips
auto-generated columns from the value list, so a user who wants to
set a serial/shortid column explicitly could only discover Form A by
reading help. Now the hint at the first Form B value slot appends a
note naming the skipped column(s) and pointing at the explicit-column
form.

hint_resolution_at_input derives the skipped columns from the
post-walk WalkContext (Form B = no user_listed_columns + table has
serial/shortid columns) and reports them on HintResolution; the note
fires only at the first slot so it doesn't repeat at every comma.
ambient_hint composes it onto the per-column prose.

src/friendly/strings/en-US.yaml

@@ -312,6 +312,11 @@ hint:
   # actual column name so the user sees "for `Email`: Type a
   # quoted string …" instead of the generic type prose.
   value_slot_for_column: "for `{column}`: {detail}"
+  # Pedagogical note appended at the first value slot of a
+  # Form B `insert into T values (…)` when T has auto-generated
+  # columns the value list skips — points the user at the
+  # explicit-column form so the skipped column is discoverable.
+  value_slot_autogen_skipped: "({columns} auto-generated — skipped here; list columns explicitly, e.g. `insert into T (...) values (...)`, to set it.)"
 
 parse:
   # Wrapper around chumsky's structural error message. The