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/r6_source.rs

@@ -26,7 +26,9 @@ fn authored_v3_bundle_upgrade_preserves_includes_nested_ownership_comments_and_i
     };
     let compiled = compile_bundle(&bundle, ProjectLimits::default()).unwrap();
     assert_eq!(compiled.bundle.files.len(), 2);
-    assert!(compiled.bundle.files["project.arcadia"].contains("arcadia 6;"));
+    assert!(
+        compiled.bundle.files["project.arcadia"].contains(&format!("arcadia {SCHEMA_VERSION};"))
+    );
     assert!(compiled.bundle.files["project.arcadia"].contains("include \"contracts.arcadia\";"));
     for text in [
         "// Contracts stay in their original module.",