feat(encode): write the TOML 1.1 output form

Assisted-by: DeepSeek V4.1 Flash

interpres.go

@@ -232,7 +232,10 @@ type Unmarshaler interface {
 //     inline table.
 //   - Scalars encode as TOML scalars: bool, int64, float64, string, time.Time
 //     (offset date-time), and LocalDateTime/LocalDate/LocalTime (local
-//     variants).
+//     variants). A date-time writes its seconds only when the value carries
+//     them, and drops the trailing zeros of a fractional second.
+//   - A table element of a value array is written as an inline table, across
+//     lines when it does not fit one.
 //   - Values implementing Marshaler are encoded by calling MarshalTOML and
 //     using its result.
 //   - Values implementing encoding.TextMarshaler, and not one of the
@@ -261,8 +264,8 @@ func MarshalContext(ctx context.Context, v any) ([]byte, error) {
 
 // An Encoder encodes Go values into TOML.
 //
-// All options default to the behaviour earlier releases used, and the defaults
-// pass the toml-test compliance suite in both directions:
+// All options default to the behaviour that passes the toml-test compliance
+// suite in both directions:
 //
 //	GroupByKind:        true  (scalars first, then tables, then arrays of tables)
 //	OmitEmptyArrays:    false (a nil/empty []string slice emits [] as a value;