perf(@angular/build): avoid encoding the inline source map before remapping

`generateMap` is `generateDecodedMap` followed by encoding the mappings to VLQ, and remapping
decodes whatever it is handed. The encoded string was therefore built only to be parsed straight
back, holding two representations of the largest structure involved in inlining a file at the
point where a build is already at its peak.

`generateDecodedMap` is used instead. The mapping resolution is unchanged: `hires`, `source` and
`includeContent` are untouched, and VLQ round-trips integers exactly, so the remapped output is
byte-identical. Verified over the output of a 10MB chunk with 488 messages, whose map carries
78,036 mapping segments across 303 sources.

Author: mattlewis92

packages/angular/build/src/tools/esbuild/i18n-inliner-worker.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.dev/license
  */
 
-import remapping, { type EncodedSourceMap, type SourceMapInput } from '@ampproject/remapping';
+import remapping, { type DecodedSourceMap, type SourceMapInput } from '@ampproject/remapping';
 import { MagicString } from 'magic-string';
 import assert from 'node:assert';
 import { deserialize } from 'node:v8';
@@ -260,12 +260,15 @@ async function transformWithOxc(
   const outputCode = magicString.toString();
   let outputMap;
   if (map && magicString.hasChanged()) {
-    const rawMap = magicString.generateMap({
+    // A decoded map is generated here rather than an encoded one because remapping decodes its
+    // inputs. Encoding the mappings only for remapping to immediately decode them again doubles
+    // the peak memory of the largest structure involved in inlining a file.
+    const rawMap = magicString.generateDecodedMap({
       source: options.filename,
       includeContent: true,
       hires: 'boundary',
     });
-    outputMap = remapping([rawMap as EncodedSourceMap, map], () => null);
+    outputMap = remapping([{ ...rawMap, version: 3 } satisfies DecodedSourceMap, map], () => null);
   }
 
   return {