feat(image-list)!: replace fixed Start extras with growable value_N slots

Distributed Image List Start no longer has reference_image, text,
strength, seed or per-slot mode dropdowns. It now takes images, mask and
up to 10 generic value_N inputs (IMAGE, MASK, STRING, INT, FLOAT,
BOOLEAN) that grow via native V3 Autogrow, each with a matching output.

- One value is shared by every image; one per image pairs in order; any
  other count fails before dispatch. Only images is split into frames.
- Outputs are declared up front (image, mask, item_index, context,
  value_1..value_10). web/imageListStart.js hides unused value outputs,
  mirrors input types, and follows Autogrow compaction so downstream
  links keep their value.
- Image-list protocol bumped to v2; older workers fail preflight.

Breaking: saved workflows using the old Start inputs must recreate Start.

api/image_list_routes.py

@@ -6,6 +6,7 @@ import server
 
 from ..image_list.runtime import (
     MAX_REQUEST_BYTES,
+    PROTOCOL_VERSION,
     decode_result,
     delete_worker_item,
     set_master_result,
@@ -34,7 +35,7 @@ async def _json_body(request):
 async def image_list_capabilities_endpoint(_request):
     return web.json_response({
         "supported": True,
-        "protocol_version": 1,
+        "protocol_version": PROTOCOL_VERSION,
         "node_ids": ["DistributedImageListStart", "DistributedImageListEnd"],
         "transport": "typed-float-tensor-json-v1",
     })

api/orchestration/dispatch.py

@@ -6,6 +6,9 @@ import aiohttp
 
 from ...utils.logging import debug_log, log
 from ...utils.network import build_worker_url, get_client_session, probe_worker
+# Must match image_list.runtime.PROTOCOL_VERSION (kept local so this module
+# stays importable without the image-list runtime; a test pins them equal).
+IMAGE_LIST_PROTOCOL_VERSION = 2
 try:
     from ...utils.trace_logger import trace_debug, trace_info
 except ImportError:
@@ -215,11 +218,12 @@ async def preflight_image_list_workers(workers, require_idle=True, timeout=3.0):
                     raise RuntimeError(f"Image-list worker {worker_id} returned malformed capability data")
                 if (
                     supported is not True
-                    or protocol_version != 1
+                    or protocol_version != IMAGE_LIST_PROTOCOL_VERSION
                     or not required_nodes.issubset(nodes)
                 ):
                     raise RuntimeError(
-                        f"Image-list worker {worker_id} is incompatible: requires protocol v1 and nodes "
+                        f"Image-list worker {worker_id} is incompatible: requires protocol "
+                        f"v{IMAGE_LIST_PROTOCOL_VERSION} and nodes "
                         f"{sorted(required_nodes)}; no work was submitted"
                     )