feat(enhance): pick LoRAs from ComfyUI per job (#220)

Templates with `imageapi:lora-slot:<n>:high|low` nodes take LoRAs picked
per job from a catalog built live from ComfyUI.

- Catalog: ComfyUI's LoraLoaderModelOnly `lora_name` choices (cached
  60 s, re-read when a submit names an unknown id), paired by High/Low
  name tokens (StyleHigh/StyleLow, x-HIGH/x-LOW, x_high_noise/...). Files
  the workflow already loads outside the slots (lightx2v, switches) and
  `[template.catalog] exclude` substrings never show; ids derive from the
  names so they stay stable.
- POST /enhance `slots: [{lora, scale?}]` fills the slots in order: each
  pick sets the slot nodes' lora_name and scales their exported strength;
  unused slots run at 0, so the graph is never rewired. More picks than
  slots, duplicates or unknown ids are 400s.
- GET /enhance/templates gains `slots` and `catalog: {loras, strength,
  min, max}`; jobs store and return the picks (new enhance_jobs.lora_slots
  JSON column).

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

CLAUDE.md

@@ -460,7 +460,8 @@ auth and stays LAN-only, so ImageApi relays previews too.
   `unreachable_grace_secs`, `default_template`, `warn_above_megapixels`,
   `[[path_map]]` (`from`, `to`), `[[template]]` (`name`, `label`, `description`,
   `file`, `prompt_mode`, `prompt_join`, `output_megapixels`, `[[template.lora]]`
-  (`id`, `label`, `default`, `strength`, `min`, `max`)).
+  (`id`, `label`, `default`, `strength`, `min`, `max`), `[template.catalog]` (`strength`,
+  `min`, `max`, `exclude`)).
 - **Templates** are API-format workflow exports, read-only (never edit them from
   here). Nodes are found by `_meta.title`: `imageapi:source` (required, gets the
   photo path), `imageapi:save` (required, forced to `require_approval = true`; a
@@ -472,7 +473,12 @@ auth and stays LAN-only, so ImageApi relays previews too.
   low pair; the resolved scale multiplies each node's exported `strength_model` /
   `strength_clip` (1.0 = as exported, 0 = off, a pair keeps its ratio), never rewired; a
   node with no declaration keeps its strength, a declaration with no node isn't offered;
-  both log a startup warning). `prompt_mode = "append"`: the user's text is joined
+  both log a startup warning), `imageapi:lora-slot:<n>:high|low` (pickable LoRAs, #220:
+  each slot needs a high and a low node, numbered 1.. without gaps; picks fill them in order,
+  setting `lora_name` and scaling the exported strength, unused slots run at 0; the catalog is
+  ComfyUI's `/object_info/LoraLoaderModelOnly` list (cached 60 s, re-read when a submit names
+  an unknown id) paired by High/Low name tokens (`src/enhance/lora_catalog.rs`), minus every
+  `lora_name` the workflow loads outside the slots and `catalog.exclude` substrings). `prompt_mode = "append"`: the user's text is joined
   after the template's own prompt with `prompt_join` (default one space); empty text
   leaves the prompt as is. `"replace"`: the text *is* the prompt and is required (empty
   = 400); it needs a prompt node. With no `reference_path` the reference node **and
@@ -519,8 +525,12 @@ GET  /enhance/templates
                      "prompt_mode": "append"|"replace", "prompt_required",
                      "accepts_reference","default","output_megapixels",
                      "warn_above_megapixels", "output": "image"|"video",
-                     "loras": [{"id","label","default","strength","min","max"}]}]}
-POST /enhance  {"path","template","prompt"?,"reference_path"?,"loras"?: {id: bool|scale},"library"?}  -> job
+                     "loras": [{"id","label","default","strength","min","max"}],
+                     "slots": n, "catalog"?: {"loras": [{"id","label"}],"strength","min","max"}}]}
+POST /enhance  {"path","template","prompt"?,"reference_path"?,"loras"?: {id: bool|scale},
+                "slots"?: [{"lora": catalog id, "scale"?}],"library"?}  -> job
+     (slots: at most the template's slot count, no duplicates, unknown id = 400; no scale =
+      catalog.strength, <= 0 = slot unused)
      (true = the switch's strength, false or scale <= 0 = off, a scale is clamped to min..max;
       a missing switch uses its default; an id the template doesn't offer = 400)
 GET  /enhance/jobs/{id}              -> job
@@ -540,6 +550,7 @@ POST /enhance/jobs/{id}/discard      -> job (hidden from the list; ComfyUI untou
 
 job = {"id","status","queue_position"?,"error"?,"path","library_id","template",
        "prompt"?,"reference_path"?,"loras"?: {id: scale} (resolved, 0 = off; absent without switches),
+       "slots"?: [{"lora","label","scale"}] (picked LoRAs; absent when none),
        "created_at","updated_at",
        "run_ms": <ms ComfyUI ran it, or null until finished / when ComfyUI gave no timings>,
        "pending": [{"n","preview": "/enhance/jobs/{id}/preview/{n}","approved"}],