walker: flag LIKE on a numeric column (ADR-0027 Amendment 1)

LIKE is a text-pattern match; against a numeric column (int,
real, decimal, serial) it runs but is almost never intended.
predicate_warnings now emits a WARNING for it, spanned at the
target column. New Type::is_numeric; catalog key
diagnostic.like_numeric; ADR-0027 gains "Amendment 1" and the
adr/README index line is updated per the index-upkeep rule.

bool and the text-/blob-backed types are deliberately not
flagged — see the amendment for the rationale.

3 walker tests (int, decimal NOT LIKE, text-column clean).
1108 passing, clippy clean.

src/friendly/strings/en-US.yaml

@@ -469,6 +469,8 @@ diagnostic:
   # runs, but the comparison is very likely not intended.
   type_mismatch: "`{column}` is {type} — this comparison uses a value of a different type"
   eq_null: "`= NULL` is never true — use `IS NULL` or `IS NOT NULL`"
+  # ADR-0027 Amendment 1: LIKE is a text-pattern match.
+  like_numeric: "`{column}` is {type} — `LIKE` is a text-pattern match, not a {type} comparison"
 
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