Tune static workflows to CyberRealisticXL recommended settings

The static workflow JSONs default to CyberRealisticXLPlay (set in an
earlier commit), but the KSampler still had euler/normal/CFG7/20 — the
generic settings I scaffolded with. Updated to the creator-published
defaults: dpmpp_2m_sde / karras / CFG 4 / 28 steps. CLIP skip 1
already correct (no node needed; default behavior).

Added a section to the deployment README spelling out the trade-off:
static workflows are locked to one checkpoint family at a time because
Open WebUI's nodes mapping doesn't expose sampler/CFG/scheduler/CLIP
skip/prefix. For multi-checkpoint use, the smart_image_gen Tool path is
the only one that gets these right per-prompt.

Re-paste workflows into Open WebUI Settings → Images to pick up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

workflows/img2img.json

@@ -3,10 +3,10 @@
     "class_type": "KSampler",
     "inputs": {
       "seed": 0,
-      "steps": 20,
-      "cfg": 7,
-      "sampler_name": "euler",
-      "scheduler": "normal",
+      "steps": 28,
+      "cfg": 4.0,
+      "sampler_name": "dpmpp_2m_sde",
+      "scheduler": "karras",
       "denoise": 0.75,
       "model": ["4", 0],
       "positive": ["6", 0],

workflows/txt2img.json

@@ -3,10 +3,10 @@
     "class_type": "KSampler",
     "inputs": {
       "seed": 0,
-      "steps": 20,
-      "cfg": 7,
-      "sampler_name": "euler",
-      "scheduler": "normal",
+      "steps": 28,
+      "cfg": 4.0,
+      "sampler_name": "dpmpp_2m_sde",
+      "scheduler": "karras",
       "denoise": 1,
       "model": ["4", 0],
       "positive": ["6", 0],