Checkpoint source 7 workflows and in-progress diagram authoring redesign

Preserve current core, source, REST, desktop, recovery, documentation and validation work, including AGENTS.md and the development summary. This is a work-in-progress checkpoint: the new compact palette has outstanding compilation errors and native acceptance; earlier passing gates retain their documented scope.

crates/oa-core/tests/source_project.rs

@@ -163,7 +163,9 @@ fn cross_file_typed_ports_global_forward_references_and_stable_ids() {
         (5, oa_core::SCHEMA_VERSION)
     );
     assert!(input.files[&input.entry].contains("arcadia 5;"));
-    assert!(result.bundle.files[&result.bundle.entry].contains("arcadia 6;"));
+    assert!(
+        result.bundle.files[&result.bundle.entry].contains(&format!("arcadia {SCHEMA_VERSION};"))
+    );
     assert!(
         again.decoded.migration.is_none(),
         "stabilized current source must not migrate twice"