fix: add ConditioningZeroOut for FLUX workflow negative input

FLUX models require negative conditioning even though they don't use it.
Added ConditioningZeroOut node to create empty negative conditioning from
positive output, satisfying KSampler's required negative input.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

comfyui/workflows/text-to-image/flux-dev-t2i-production-v1.json

@@ -1,6 +1,6 @@
 {
-  "last_node_id": 8,
-  "last_link_id": 12,
+  "last_node_id": 9,
+  "last_link_id": 13,
   "nodes": [
     {
       "id": 1,
@@ -80,13 +80,41 @@
       "title": "API Positive Prompt"
     },
     {
-      "id": 4,
-      "type": "EmptyLatentImage",
+      "id": 9,
+      "type": "ConditioningZeroOut",
       "pos": [450, 400],
-      "size": [315, 106],
+      "size": [315, 60],
       "flags": {},
       "order": 3,
       "mode": 0,
+      "inputs": [
+        {
+          "name": "conditioning",
+          "type": "CONDITIONING",
+          "link": 8
+        }
+      ],
+      "outputs": [
+        {
+          "name": "CONDITIONING",
+          "type": "CONDITIONING",
+          "links": [9],
+          "slot_index": 0
+        }
+      ],
+      "properties": {
+        "Node name for S&R": "ConditioningZeroOut"
+      },
+      "title": "Empty Negative Conditioning"
+    },
+    {
+      "id": 4,
+      "type": "EmptyLatentImage",
+      "pos": [450, 500],
+      "size": [315, 106],
+      "flags": {},
+      "order": 4,
+      "mode": 0,
       "outputs": [
         {
           "name": "LATENT",
@@ -107,7 +135,7 @@
       "pos": [900, 100],
       "size": [315, 474],
       "flags": {},
-      "order": 4,
+      "order": 5,
       "mode": 0,
       "inputs": [
         {
@@ -123,7 +151,7 @@
         {
           "name": "negative",
           "type": "CONDITIONING",
-          "link": null
+          "link": 9
         },
         {
           "name": "latent_image",
@@ -151,7 +179,7 @@
       "pos": [900, 600],
       "size": [315, 60],
       "flags": {},
-      "order": 5,
+      "order": 6,
       "mode": 0,
       "outputs": [
         {
@@ -173,7 +201,7 @@
       "pos": [1270, 100],
       "size": [210, 46],
       "flags": {},
-      "order": 6,
+      "order": 7,
       "mode": 0,
       "inputs": [
         {
@@ -206,7 +234,7 @@
       "pos": [1530, 100],
       "size": [400, 100],
       "flags": {},
-      "order": 7,
+      "order": 8,
       "mode": 0,
       "inputs": [
         {
@@ -229,7 +257,9 @@
     [4, 4, 0, 5, 3, "LATENT"],
     [5, 5, 0, 7, 0, "LATENT"],
     [6, 6, 0, 7, 1, "VAE"],
-    [7, 7, 0, 8, 0, "IMAGE"]
+    [7, 7, 0, 8, 0, "IMAGE"],
+    [8, 3, 0, 9, 0, "CONDITIONING"],
+    [9, 9, 0, 5, 2, "CONDITIONING"]
   ],
   "groups": [],
   "config": {},