Add bilingual manual and localized docs routes

doc/manual/source/language/modules-and-imports.md

@@ -0,0 +1,88 @@
+# Modules and Imports
+
+`import` returns a DCDL module or structured value resolved by the host.
+
+## Syntax
+
+```dcdl
+import "./config.dcdl"
+```
+
+An import specifier is a string literal.
+The host decides whether a specifier represents a path, URL, resource name, or another form of identifier.
+
+## Modules
+
+A sequence of field definitions at the top level creates a recursive module scope.
+A top-level field can refer to another top-level field in the same module by identifier.
+
+```dcdl
+schema = {
+    name = String;
+};
+
+result = schema;
+```
+
+Fields in an ordinary object literal do not implicitly refer to sibling fields by identifier.
+To reference a value from inside an object, use a binding in an outer scope or an explicit path reference.
+
+Modules and their fields are evaluated lazily.
+An unreferenced field of an imported module is not evaluated.
+
+## Host-defined resolution
+
+Decodal does not define filesystem or network rules for import specifiers.
+The host receives the importing module and specifier, then returns one of:
+
+- DCDL source
+- A structured value constructed by the host
+
+The latter allows a host to parse Markdown, JSON, TOML, and other formats according to its own rules and expose the result as an ordinary Decodal value.
+
+```dcdl
+Post = {
+    frontmatter = {
+        title = String;
+        draft = Bool default false;
+    };
+    body = String;
+};
+
+post = (import "./hello.md") as Post;
+```
+
+Structured values follow the same rules as source-derived values for path references, composition, constraint validation, and materialization.
+See [Embedding](../embedding.md#imports) for the loader API and diagnostic provenance.
+
+## Cyclic imports
+
+Modules may import one another cyclically as long as the dependency graph of the fields actually evaluated is not cyclic.
+
+```dcdl
+# main.dcdl
+schema = {
+    name = String;
+};
+
+result = (import "./func.dcdl")(schema);
+```
+
+```dcdl
+# func.dcdl
+(input: (import "./main.dcdl").schema) => input
+```
+
+Here, `func.dcdl` imports `main.dcdl`, but the referenced `schema` does not depend on `result`, so evaluation succeeds.
+Reaching the same field again while it is being evaluated produces a cycle-dependency diagnostic.
+
+## Import failures
+
+The following conditions produce an import failure:
+
+- The host cannot resolve the specifier.
+- The resource cannot be read.
+- Parsing DCDL source fails.
+- A required value in the imported module cannot be evaluated.
+- Reading or converting a structured value fails.
+- The evaluated dependency graph is cyclic.