[feat] Enable declarationMap for source file mapping in API changelog

Generate declaration maps to enable mapping from generated .d.ts files
back to source files. This will allow the API changelog to link to actual
source code locations instead of generated declaration files.

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

Co-Authored-By: Claude <noreply@anthropic.com>

tsconfig.types.json

@@ -2,6 +2,7 @@
   "extends": "./tsconfig.json",
   "compilerOptions": {
     "declaration": true,
+    "declarationMap": true,
     "noEmit": false,
     "paths": {
       "@/*": ["./src/*"]