🔧 Inline sources and drop declaration maps

The JS source maps now embed their sources (inlineSources), so a debugger
resolves into src/ even though the package ships only dist/. declarationMap
is dropped: a .d.ts.map cannot embed source and would dangle against the
unshipped src/.

Also removes a duplicate backlog entry for the same task and closes the
sourcemap item.

tsconfig.build.json

@@ -4,8 +4,8 @@
         "noEmit": false,
         "target": "es2024",
         "declaration": true,
-        "declarationMap": true,
         "sourceMap": true,
+        "inlineSources": true,
         "outDir": "dist",
         "rewriteRelativeImportExtensions": true,
         "rootDir": "src"