feat(enhance): LoRA strength scale alongside the on/off switch (#218)

So the app builds against the final shape: each [[template.lora]] gains
`strength` (the scale when on, default 1.0) and `min` / `max` (the
slider's range, default 0.0-1.5).

- POST /enhance `loras` takes true / false or a scale: true = strength,
  false or <= 0 = off, a scale is clamped to min..max.
- The scale multiplies each node's exported strength_model /
  strength_clip, so 1.0 = as exported and a high/low pair keeps its
  ratio.
- Jobs and the job view store the resolved scale per id (0 = off);
  GET /enhance/templates lists strength, min and max.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

enhance.example.toml

@@ -64,11 +64,14 @@ prompt_mode = "replace"
 # label = "Restore (Dev, slow)"
 # file = "/media/nas/image_fibo2_restore_imageapi_API.json"
 
-# A video template with optional LoRAs the app can switch on or off (#218).
-# Each [[template.lora]] matches the workflow's LoRA loader nodes titled
-# "imageapi:lora:<id>" (Wan's high- and low-noise pair share one id). Off sets
-# their strength_model (and strength_clip) to 0; the graph isn't rewired.
-# Nodes titled that way with no entry here keep their exported strength.
+# A video template with optional LoRAs the app can switch on or off and scale
+# (#218). Each [[template.lora]] matches the workflow's LoRA loader nodes titled
+# "imageapi:lora:<id>" (Wan's high- and low-noise pair share one id). The
+# request's scale multiplies each node's exported strength_model (and
+# strength_clip), so 1.0 = as exported, 0 = off and a pair keeps its ratio; the
+# graph isn't rewired. Any number of switches can be on at once (LoRA patches
+# add up, so their order in the graph doesn't matter). Nodes titled that way
+# with no entry here keep their exported strength.
 [[template]]
 name = "animate"
 label = "Animate"
@@ -81,3 +84,6 @@ output_megapixels = 0.92
 id = "style"                         # node title "imageapi:lora:style"
 label = "Style"
 default = false                      # default: false; used when the request omits it
+strength = 1.0                       # default: 1.0; the scale when on without a number
+min = 0.0                            # default: 0.0; slider range while on (a requested
+max = 1.5                            # default: 1.5;  scale is clamped; <= 0 is off)