fix(es/codegen): Restore missing top-level comments (#11302)

This fixes an issue where top-level comments (like copyright headers)
were being lost after PR #11199 changed Module/Script spans to start at
position 0.

The fix skips emitting leading comments at Module/Script level when the
body is non-empty. Instead, comments are emitted by the first body item
with a real source span. Injected imports have DUMMY_SP, so they skip
comment emission, and original source items emit their comments
correctly after the imports.

Closes #11167

🤖 Generated with [Claude Code](https://claude.ai/code)

---------

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Donny/강동윤 <[email protected]>

Author: kdy1

.changeset/few-bees-crash.md

@@ -1 +1,2 @@
 //// [ambientAccessors.ts]
+// ok to use accessors in ambient class in ES3

crates/swc/tests/tsc-references/ambientAccessors.1.normal.js

@@ -1,5 +1,6 @@
 //// [ambientDeclarationsExternal.ts]
 //// [decls.ts]
+// Ambient external module with export assignment
  // Ambient external import declaration referencing ambient external module using top level module name
 //// [consumer.ts]
 //!   x Import assignment cannot be used when targeting ECMAScript modules. Consider using `import * as ns from "mod"`, `import {a} from "mod"`, `import d from "mod"`, or another module format instead.

crates/swc/tests/tsc-references/ambientDeclarationsExternal.1.normal.js

@@ -1 +1,2 @@
 //// [ambientEnumDeclaration1.ts]
+// In ambient enum declarations, all values specified in enum member declarations must be classified as constant enum expressions.

crates/swc/tests/tsc-references/ambientEnumDeclaration1.1.normal.js

@@ -1 +1,3 @@
 //// [ambientEnumDeclaration2.ts]
+// In ambient enum declarations that specify no const modifier, enum member declarations
+// that omit a value are considered computed members (as opposed to having auto- incremented values assigned).

crates/swc/tests/tsc-references/ambientEnumDeclaration2.1.normal.js

@@ -12,3 +12,4 @@ var o = [
 ]);
 export { };
 //// [tslib.d.ts]
+// this is a pre-TS4.4 versions of emit helper, which always forced array packing

crates/swc/tests/tsc-references/arraySpreadImportHelpers.1.normal.js

@@ -1 +1,3 @@
 //// [callSignaturesThatDifferOnlyByReturnType3.ts]
+// Normally it is an error to have multiple overloads with identical signatures in a single type declaration.
+// Here the multiple overloads come from multiple merged declarations.

crates/swc/tests/tsc-references/callSignaturesThatDifferOnlyByReturnType3.1.normal.js

@@ -1 +1,4 @@
 //// [constEnum1.ts]
+// An enum declaration that specifies a const modifier is a constant enum declaration.
+// In a constant enum declaration, all members must have constant values and
+// it is an error for a member declaration to specify an expression that isn't classified as a constant enum expression.

crates/swc/tests/tsc-references/constEnum1.1.normal.js

@@ -1 +1,2 @@
 //// [derivedInterfaceDoesNotHideBaseSignatures.ts]
+// Derived interfaces no longer hide signatures from base types, so these signatures are always compatible.

crates/swc/tests/tsc-references/derivedInterfaceDoesNotHideBaseSignatures.1.normal.js

@@ -1,4 +1,5 @@
 //// [lovefield-ts.d.ts]
+// bug #27352, crashes from github.com/google/lovefield
 //// [enums.js]
 lf.Order = {};
 lf.Order.DESC = 0;