Fix Z-Image 3070 fast-start workflow

optimized/text-to-image/zimage-turbo-3070-fast-start/README.md

@@ -13,8 +13,10 @@ This master stays close to the official `Z-Image Turbo` example because that is
 
 ## Workflow asset
 
+- `workflow.json`
 - `workflow.png`
-- Load it by dragging the PNG into ComfyUI.
+- Prefer `workflow.json` for current testing and editing.
+- `workflow.png` is the original embedded example import.
 
 ## Direct test command
 
@@ -22,7 +24,7 @@ You can also submit it straight to the live ComfyUI server with:
 
 `node scripts/submit-workflow-test.mjs --workflow optimized/text-to-image/zimage-turbo-3070-fast-start/workflow.png --prompt "<your prompt>"`
 
-That path reads the embedded PNG `prompt` chunk, applies text-to-image overrides, submits the job, polls history, and downloads the outputs locally.
+That path reads either the JSON workflow or the embedded PNG `prompt` chunk, applies text-to-image overrides, submits the job, polls history, and downloads the outputs locally.
 
 ## Built from
 
@@ -38,7 +40,14 @@ That path reads the embedded PNG `prompt` chunk, applies text-to-image overrides
 
 - Official model wiring
 - Official `qwen_3_4b` text encoder path
-- Embedded PNG workflow format for easy import
+- The original embedded PNG workflow as a reference import
+
+## What I intentionally changed
+
+- switched the maintained test target to `workflow.json`
+- repointed the loader names to the live server filenames
+- lowered the default latent size to `768x768`
+- lowered the default sampler steps to `6`
 
 ## What I intentionally did not add yet