Extract database schema to separate SQL file

- Move schema from database.go to schema.sql
- Use go:embed to include schema at compile time
- Add 'out' debug file to .gitignore

This makes the schema more maintainable and easier to review.

.gitignore

@@ -31,4 +31,7 @@ go.work.sum
 *.tmp
 
 # Raw AS data (we only commit the gzipped version)
-pkg/asinfo/asdata.json
+pkg/asinfo/asdata.json
+
+# Debug output files
+out