build: emit sourcemaps for CJS and ESM builds

Enable sourceMap, declarationMap, and inlineSources in the shared
tsconfig so both build flavors emit .js.map and .d.ts.map files with
TypeScript sources embedded. Maps ship automatically via the existing
files: ["dist"] entry in package.json, giving consumers readable
stack traces pointing at src/*.ts.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: buffcode

tsconfig.base.json

@@ -12,7 +12,10 @@
     "noEmitOnError": true,
     "noImplicitAny": true,
     "noImplicitReturns": true,
-    "declaration": true
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true,
+    "inlineSources": true
   },
   "include": [
     "./src/**/*"