fix(browser): omit erased type-only import-equals from source-map dependencies (#4165)

Source-map original-source parsing reported `import type X = require("m")`
as a require dependency, although TypeScript erases the declaration. The
fetcher re-derived import-equals targets instead of using the existing
value-only rule. That rule now lives with the other type-only module
declaration predicates in javascriptModuleDeclaration, and the fetcher,
static analysis, and semantic analysis all use it.

Fixes #3932

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/domain/javascript/javascriptModuleDeclaration.ts

@@ -16,6 +16,19 @@ export const isTypeOnlyExportDeclaration = (
       t.isTSTypeAliasDeclaration(node.declaration) ||
       t.isTSDeclareFunction(node.declaration)));
 
+/**
+ * Runtime external-module target for a value import-equals declaration;
+ * `import type X = require("m")` is erased and declares no dependency.
+ */
+export const semanticImportEqualsSpecifier = (
+  node: t.TSImportEqualsDeclaration,
+): string | null =>
+  node.importKind !== "type" &&
+  t.isTSExternalModuleReference(node.moduleReference) &&
+  t.isStringLiteral(node.moduleReference.expression)
+    ? node.moduleReference.expression.value
+    : null;
+
 /** Whether this import binding is explicitly type-only. */
 export const isTypeOnlyImportSpecifier = (node: t.ImportSpecifier): boolean =>
   node.importKind === "type" || node.importKind === "typeof";