Make participant ports and hierarchical model navigation discoverable

Add focused containment browsing, contextual paged search, clear outline depth and direct component-port creation and connection actions. Share exact boundary feasibility checks to avoid whole-project validation for each picker candidate. Preserve source/property drafts and interrupted-save recovery state, document source-project behavior, and record Windows/Linux native verification and independent review fixes.

crates/oa-core/src/validation.rs

@@ -2385,6 +2385,29 @@ pub fn can_connect(p: &Project, kind: RelationKind, source: Id, target: Id) -> b
     }
     !issues.iter().any(|i| i.severity == Severity::Error)
 }
+
+/// Feasibility for a boundary exchange with its actual orientation. This checks
+/// only the proposed relationship, so endpoint pickers need not clone and
+/// revalidate the complete model for every port. Legacy directions remain fixed
+/// even when the exchange is unoriented.
+pub fn can_connect_boundary(p: &Project, source: Id, target: Id, oriented: bool) -> bool {
+    let candidate = Relation {
+        id: Id::nil(),
+        alias: "candidate".into(),
+        name: String::new(),
+        description: String::new(),
+        body: RelationBody::BoundaryExchange {
+            source,
+            target,
+            oriented,
+            items: vec![],
+        },
+    };
+    let mut issues = vec![];
+    validate_relation(p, &candidate, &mut issues);
+    validate_relation_context(p, &candidate, &mut issues);
+    !issues.iter().any(|i| i.severity == Severity::Error)
+}
 /// Aggregate display information only; this never creates inherited allocations.
 pub fn allocation_summary(p: &Project, work: Id) -> Option<Id> {
     let root = p.elements.get(&work)?;