transport: add spec references for fork selection and pinning

Add AIT-CT13e and AIT-CT13f spec point references to the view's
fork auto-selection and selection pinning code paths. Update the
specification submodule with the corresponding new spec points
and View-based API revisions.

Author: mschristensen

specification

@@ -262,6 +262,7 @@ export class DefaultView<TEvent, TMessage> implements View<TEvent, TMessage> {
 
     const result = await this._sendDelegate(input, options, { flattenNodes: () => this.flattenNodes() });
 
+    // Spec: AIT-CT13e
     // Auto-select the new fork in this view when creating a fork.
     // The delegate's optimistic insert created the sibling — pin this
     // view to the latest (new) sibling so the user sees their edit/regeneration.
@@ -560,6 +561,7 @@ export class DefaultView<TEvent, TMessage> implements View<TEvent, TMessage> {
       if (!this._tree.hasSiblings(msgId)) continue;
       const groupRoot = this._tree.getGroupRoot(msgId);
 
+      // Spec: AIT-CT13e
       // Check if this fork was initiated by this view (e.g. regenerate).
       // If so, select the newest sibling and clear the pending state.
       // The pending set stores the forkOf msgId (the group root), but the
@@ -573,6 +575,8 @@ export class DefaultView<TEvent, TMessage> implements View<TEvent, TMessage> {
         continue;
       }
 
+      // Spec: AIT-CT13f
+      // External fork — pin to the currently-visible sibling.
       if (this._selections.has(groupRoot)) continue;
       const idx = this._tree.getSiblingIndex(msgId);
       if (idx >= 0) {