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/coverage_diagnostics.rs

@@ -56,6 +56,7 @@ fn occurrence(p: &mut Project, owner: Id, body: OccurrenceBody) -> Id {
 }
 fn exchange(id: Id) -> OccurrenceBody {
     OccurrenceBody::Exchange {
+        operation: None,
         exchange: Some(id),
         sender: None,
         receiver: None,
@@ -183,6 +184,7 @@ fn included_process_and_nested_scenario_evidence_is_identity_based_in_both_layer
             &mut p,
             branch,
             OccurrenceBody::Exchange {
+                operation: None,
                 exchange: Some(e),
                 sender: Some(sender),
                 receiver: Some(receiver),
@@ -195,6 +197,7 @@ fn included_process_and_nested_scenario_evidence_is_identity_based_in_both_layer
             &mut p,
             branch,
             OccurrenceBody::Exchange {
+                operation: None,
                 exchange: Some(e),
                 sender: Some(receiver),
                 receiver: Some(sender),