refactor: rename the encoder layout options

Assisted-by: GLM 5.3 Flash

docs/API.md

@@ -555,11 +555,11 @@ parsed as keys of the sub-table.
 
 ### Preserving declaration order
 
-`GroupByKind(false)` on an `Encoder` walks the entries in declaration order
+`LayoutKindDeclaration` on an `Encoder` walks the entries in declaration order
 instead, emitting each header immediately before its content:
 
 ```go
-out, err := interpres.NewEncoder().GroupByKind(false).Marshal(cfg)
+out, err := interpres.NewEncoder().Layout(interpres.LayoutKindDeclaration).Marshal(cfg)
 ```
 
 The output remains parseable, but a scalar declared after a sub-table lands
@@ -650,12 +650,12 @@ omitted, because TOML forbids an empty `[[a]]`. Other empty arrays emit as
 ### Long strings
 
 By default every string is emitted as a basic `"..."` string with the escapes
-TOML requires, a newline among them as `\n`. `UseLiteralMultiline(threshold)`
+TOML requires, a newline among them as `\n`. `LiteralMultiline(threshold)`
 switches strings that contain a newline and are at least `threshold` bytes long
 to the literal `'''...'''` form, which carries the newlines verbatim:
 
 ```go
-out, err := interpres.NewEncoder().UseLiteralMultiline(80).Marshal(cfg)
+out, err := interpres.NewEncoder().LiteralMultiline(80).Marshal(cfg)
 ```
 
 Single-line strings keep the basic form regardless of the threshold, and a
@@ -826,17 +826,17 @@ encoder:
 
 | Method | Default | Effect |
 |---|---|---|
-| `GroupByKind(v bool)` | `true` | group entries as scalars, then sub-tables, then arrays of tables; `false` preserves declaration order |
+| `Layout(kind LayoutKind)` | `LayoutKindGrouped` | group entries as scalars, then sub-tables, then arrays of tables; `LayoutKindDeclaration` preserves declaration order |
 | `OmitEmptyArrays()` | off | skip `key = []` for empty scalar arrays |
-| `UseLiteralMultiline(threshold int)` | `0` | emit multi-line strings of at least `threshold` bytes as literal `'''...'''` |
+| `LiteralMultiline(threshold int)` | `0` | emit multi-line strings of at least `threshold` bytes as literal `'''...'''` |
 | `InlineTables(threshold int)` | `0` | write a sub-table inline when its single-line form is at most `threshold` bytes |
 | `EmitFieldComments()` | off | print the `comment=` tag option of a field above its line or header |
 
 ```go
 out, err := interpres.NewEncoder().
-	GroupByKind(false).
+	Layout(interpres.LayoutKindDeclaration).
 	OmitEmptyArrays().
-	UseLiteralMultiline(80).
+	LiteralMultiline(80).
 	InlineTables(60).
 	MarshalContext(ctx, cfg)
 ```

docs/ARCHITECTURE.md

@@ -77,7 +77,7 @@ sequenceDiagram
 ```
 
 Encoding walks the other way. `encode.go` first builds a `tomlDoc` from the
-value, then emits it; the two phases are why `GroupByKind` can reorder entries
+value, then emits it; the two phases are why `Layout` can reorder entries
 without a second reflection pass, and why cancellation is checked during both.
 
 ```mermaid