Add isEmpty() helpers across all modules with clearable state.

Seventh expansion pass: domain-specific isEmpty() after moduleSnapshot on every module that has clearAll(), using existing count/snapshot helpers (async variants for temporal, spatial, semantic-vector, and reactive-state indexes).

Co-authored-by: Cursor <[email protected]>

pear-platform/hyper-bare-headless-ui/index.js

@@ -124,6 +124,11 @@ class HyperBareHeadlessUi extends EventEmitter {
     return this.snapshot()
   }
 
+  isEmpty () {
+    const s = this.snapshot()
+    return !s.pipeOpen && !s.ui
+  }
+
   sendToUiBatch (messages) {
     if (!Array.isArray(messages)) throw new Error('messages array required')
     return messages.map((m) => this.sendToUi(m.channel, m.payload))