fix(compiler): silence INVALID_ANNOTATION and SOURCEMAP_BROKEN warnings from workerPlugin (#6718)

* fix(compiler): drop invalid @__PURE__ before import.meta in workerPlugin

The /*@__PURE__*/ annotation is only meaningful in front of call or
new expressions. In getWorkerMain and getInlineWorker it was placed
before an import.meta.ROLLUP_FILE_URL_* property access, which Rollup
cannot interpret and silently strips with an INVALID_ANNOTATION warning
on every build of a project that uses *.worker.ts entries.

Drop the unused annotation on the workerPath assignment. The remaining
PURE markers on the createWorker(...) / createWorkerProxy(...) calls
are unchanged.

* fix(compiler): emit noop sourcemap from workerPlugin transform

The workerPlugin transform hook returned synthetic wrapper code without
a sourcemap, triggering a SOURCEMAP_BROKEN warning from Rollup for every
project that builds a *.worker.ts entry. The Rollup plugin convention
for transforms that produce code with no useful source-position mapping
is to return an empty mappings string; do that for all five transform
return paths (the mocked hydrate/worker-platform branch and the four
real-bundle branches).

---------

Co-authored-by: oliver <oliver@bitcaster.de>

Author: Scan0815

src/compiler/bundle/worker-plugin.ts

@@ -19,7 +19,10 @@ export const workerPlugin = (
       name: 'workerPlugin',
       transform(_, id) {
         if (id.endsWith('?worker') || id.endsWith('?worker-inline')) {
-          return getMockedWorkerMain();
+          return {
+            code: getMockedWorkerMain(),
+            map: { mappings: '' },
+          };
         }
         return null;
       },
@@ -77,6 +80,7 @@ export const workerPlugin = (
         dependencies.forEach((id) => this.addWatchFile(id));
         return {
           code: getWorkerMain(referenceId, workerName, workerMsgId),
+          map: { mappings: '' },
           moduleSideEffects: false,
         };
       } else if (id.endsWith('?worker-inline')) {
@@ -98,6 +102,7 @@ export const workerPlugin = (
         dependencies.forEach((id) => this.addWatchFile(id));
         return {
           code: getInlineWorker(referenceId, workerName, workerMsgId),
+          map: { mappings: '' },
           moduleSideEffects: false,
         };
       }
@@ -110,11 +115,13 @@ export const workerPlugin = (
           if (inlineWorkers) {
             return {
               code: getInlineWorkerProxy(workerEntryPath, worker.workerMsgId, worker.exports),
+              map: { mappings: '' },
               moduleSideEffects: false,
             };
           } else {
             return {
               code: getWorkerProxy(workerEntryPath, worker.exports),
+              map: { mappings: '' },
               moduleSideEffects: false,
             };
           }
@@ -405,7 +412,7 @@ const getWorkerMain = (referenceId: string, workerName: string, workerMsgId: str
 import { createWorker } from '${WORKER_HELPER_ID}';
 export const workerName = '${workerName}';
 export const workerMsgId = '${workerMsgId}';
-export const workerPath = /*@__PURE__*/import.meta.ROLLUP_FILE_URL_${referenceId};
+export const workerPath = import.meta.ROLLUP_FILE_URL_${referenceId};
 export const worker = /*@__PURE__*/createWorker(workerPath, workerName, workerMsgId);
 `;
 };
@@ -415,7 +422,7 @@ const getInlineWorker = (referenceId: string, workerName: string, workerMsgId: s
 import { createWorker } from '${WORKER_HELPER_ID}';
 export const workerName = '${workerName}';
 export const workerMsgId = '${workerMsgId}';
-export const workerPath = /*@__PURE__*/import.meta.ROLLUP_FILE_URL_${referenceId};
+export const workerPath = import.meta.ROLLUP_FILE_URL_${referenceId};
 export let worker;
 try {
   // first try directly starting the worker with the URL