fix: use selectFirstNodeByTitles to avoid strict mode violations

The default workflow has 2 CLIP Text Encode (Prompt) nodes.
Using selectNodes(['KSampler', 'CLIP Text Encode (Prompt)']) selected
all 3 nodes (1 KSampler + 2 CLIP) instead of just 2.

Added selectFirstNodeByTitles helper that only selects the first
matching node for each title, avoiding strict mode violations.

Amp-Thread-ID: https://ampcode.com/threads/T-019c177d-06bf-779a-9c72-51a3626e4659

browser_tests/fixtures/ComfyPage.ts

@@ -1384,6 +1384,18 @@ export class ComfyPage {
     await this.nextFrame()
   }
 
+  async selectFirstNodeByTitles(nodeTitles: string[]) {
+    await this.page.keyboard.down('Control')
+    for (const nodeTitle of nodeTitles) {
+      const nodes = await this.getNodeRefsByTitle(nodeTitle)
+      if (nodes.length > 0) {
+        await nodes[0].click('title')
+      }
+    }
+    await this.page.keyboard.up('Control')
+    await this.nextFrame()
+  }
+
   async select2Nodes() {
     // Select 2 CLIP nodes.
     await this.page.keyboard.down('Control')