fix: upgrade build metadata failure log from debug to warn (#127)

Metadata persistence failures may indicate disk issues and should be
visible to users, not hidden behind debug-level logging.

Impact: 1 functions changed, 1 affected

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: carlos-alm

src/builder.js

@@ -1043,7 +1043,7 @@ export async function buildGraph(rootDir, opts = {}) {
       built_at: new Date().toISOString(),
     });
   } catch (err) {
-    debug(`Failed to write build metadata: ${err.message}`);
+    warn(`Failed to write build metadata: ${err.message}`);
   }
 
   closeDb(db);