refactor: rename DTree to DValue

site/doc/pages/yaml_encode.txt

@@ -1,5 +1,5 @@
 :sig
-String yaml_encode(DTree t)
+String yaml_encode(DValue t)
 
 :params
 t : tree to serialize as YAML
@@ -10,10 +10,10 @@ return value : YAML string
 yaml_decode
 json_encode
 xml_encode
-0_DTree
+0_DValue
 
 :content
-Serializes a `DTree` into a compact YAML string for configuration files.
+Serializes a `DValue` into a compact YAML string for configuration files.
 
 `yaml_encode()` focuses on the ordinary data shapes UCE apps use for config: nested maps, lists, strings, booleans, and numeric `f64` values. It does not emit YAML tags, anchors, aliases, or custom schema features.
 
@@ -22,12 +22,12 @@ Try the live example in the [YAML demo](../demo/yaml.uce).
 Example:
 
 ```uce
-DTree cfg;
+DValue cfg;
 cfg["app"]["name"] = "UCE Starter";
 cfg["app"]["debug"].set_bool(true);
 cfg["app"]["port"] = (f64)8080;
 
-DTree path;
+DValue path;
 path = "site";
 cfg["app"]["paths"].push(path);
 path = "cache";
@@ -50,8 +50,8 @@ app:
 
 Notes:
 
-- Map keys are emitted in `DTree` map iteration order.
+- Map keys are emitted in `DValue` map iteration order.
 - Strings are left plain when safe and quoted when needed.
 - Multiline strings are emitted as literal block scalars with `|`.
 - Empty strings are emitted as `""` so they are not confused with YAML null.
-- Decoded numeric-looking config values are strings unless the original `DTree` value was explicitly numeric.
+- Decoded numeric-looking config values are strings unless the original `DValue` value was explicitly numeric.