Re-export normalizeLinkToImage and fix root @id resolution

Export normalizeLinkToImage from @fedify/vocab entry point and use
the pre-resolved _resolvedUrl for the root instance id instead of
constructing a new URL directly.  Also fix a JSDoc {@link} tag in
schema.ts.

  #793 (comment)
  #793 (comment)
  #793 (comment)

Assisted-by: OpenCode:deepseek-v4-pro

Author: dahlia

packages/vocab-tools/src/codec.ts

@@ -437,7 +437,7 @@ export async function* generateDecoder(
   if (type.extends == null) {
     yield `
     const instance = new this(
-      { id: "@id" in values ? new URL(values["@id"] as string) : undefined },
+      { id: _resolvedUrl },
       options,
     );
     `;

packages/vocab-tools/src/schema.ts

@@ -129,7 +129,7 @@ export interface PropertySchemaBase {
    * property's declared range, `undefined` when it did not handle the value,
    * or an `Error` when it recognized the value but failed while converting it.
    *
-   * {@link module} is resolved from the generated vocabulary source file
+   * `module` is resolved from the generated vocabulary source file
    * and imported dynamically at decode time.
    */
   preprocessors?: PropertyPreprocessorSchema[];

packages/vocab/src/mod.ts

@@ -53,6 +53,7 @@ export * from "./actor.ts";
 export * from "./constants.ts";
 export * from "./handle.ts";
 export * from "./lookup.ts";
+export * from "./preprocessors.ts";
 export * from "./type.ts";
 export * from "./vocab.ts";
 export { LanguageString } from "@fedify/vocab-runtime";