Move negative prompt into static/negative_prompt.txt

Editorial content — easier to tune without touching inference logic.
Read once at startup alongside other static files.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -363,7 +363,6 @@ def infer(images_b64_json, prompt, seed, randomize_seed, guidance_scale, steps,
     if randomize_seed:
         seed = random.randint(0, MAX_SEED)
     generator = torch.Generator(device=device).manual_seed(seed)
-    negative_prompt = "worst quality, low quality, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, jpeg artifacts, signature, watermark, username, blurry"
     width, height = update_dimensions_on_upload(pil_images[0])
     print(f"[infer] input={pil_images[0].size}, output={width}x{height}, seed={seed}")
 
@@ -434,6 +433,9 @@ with open("static/wire_outputs.js") as _f:
 with open("static/run_preprocess.js") as _f:
     run_preprocess_js = _f.read()
 
+with open("static/negative_prompt.txt") as _f:
+    negative_prompt = _f.read().strip()
+
 # ── HTML template ──────────────────────────────────────────────────────────────
 
 with open("templates/app.html") as _f:

static/negative_prompt.txt

@@ -0,0 +1 @@
+worst quality, low quality, bad anatomy, bad hands, text, error, missing fingers, extra digit, fewer digits, cropped, jpeg artifacts, signature, watermark, username, blurry