Add code_size, data_size to generated config.json

Also simplify project config generation by skipping default fields

src/obj/mod.rs

@@ -293,4 +293,29 @@ impl ObjInfo {
             .filter(|(_, _, _, split)| split.unit == unit)
             .all(|(_, _, _, split)| split.autogenerated)
     }
+
+    /// Calculate the total size of all code sections.
+    pub fn code_size(&self) -> u32 {
+        self.sections
+            .iter()
+            .filter(|(_, section)| section.kind == ObjSectionKind::Code)
+            .map(|(_, section)| section.size as u32)
+            .sum()
+    }
+
+    /// Calculate the total size of all data sections, including common BSS symbols.
+    pub fn data_size(&self) -> u32 {
+        self.sections
+            .iter()
+            .filter(|(_, section)| section.kind != ObjSectionKind::Code)
+            .map(|(_, section)| section.size as u32)
+            .chain(
+                // Include common symbols
+                self.symbols
+                    .iter()
+                    .filter(|&symbol| symbol.flags.is_common())
+                    .map(|s| s.size as u32),
+            )
+            .sum()
+    }
 }