fix(quality): green open-sse+dashboard typecheck base-reds (#9985)

Release-equivalent fast-gates surface 5 real TS regressions inherited by the
base from merged Fal/guardrails/cursor work (fast-gates PR->release do not run
these, so they accrued on release/v3.8.50):
- open-sse/handlers/imageGeneration/providers/fal.ts: normalizeProviderImagePayload
  missing 4th 'b64_json' arg (TS2554).
- open-sse/handlers/videoGeneration/falHandler.ts: narrow video to Record before .url.
- src/app/api/v1/images/generations/route.ts: type the toJsonErrorPayload read.
- src/lib/guardrails/visionBridgeHelpers.ts: cast through unknown for UA fetch.
- src/lib/providers/mergeProviderModelListing.ts: drop index-signature requirement
  that made interface RegistryModel[] unassignable (TS2322, from #9911).

All fixed in source (keeps the gates meaningful); each reproduces on the base tip.

Co-authored-by: OmniRoute maintenance <maintainers@omniroute.local>

open-sse/handlers/imageGeneration/providers/fal.ts

@@ -89,7 +89,7 @@ export async function handleFalAIImageEdit({
     const payload = await response.json();
     const normalizedBody =
       body.response_format === undefined ? { ...body, response_format: "b64_json" } : body;
-    const imagesOut = await normalizeProviderImagePayload(payload, normalizedBody, log);
+    const imagesOut = await normalizeProviderImagePayload(payload, normalizedBody, log, "b64_json");
     return saveImageSuccessResult({
       provider,
       model: editModel,

open-sse/handlers/videoGeneration/falHandler.ts

@@ -90,7 +90,10 @@ function absoluteFalUrl(value: unknown, baseUrl: string): string | undefined {
 
 function normalizeFalVideoResponse(payload: unknown) {
   const record = payload && typeof payload === "object" ? (payload as Record<string, unknown>) : {};
-  const video = record.video && typeof record.video === "object" ? record.video : null;
+  const video =
+    record.video && typeof record.video === "object"
+      ? (record.video as Record<string, unknown>)
+      : null;
   const url = video && typeof video.url === "string" ? video.url.trim() : "";
 
   if (!url) {

src/app/api/v1/images/generations/route.ts

@@ -307,7 +307,9 @@ async function postHandler(request, context) {
     });
   }
 
-  const errorPayload = toJsonErrorPayload((result as any).error, "Image generation provider error");
+  const errorPayload = toJsonErrorPayload((result as any).error, "Image generation provider error") as {
+    error?: { message?: string };
+  };
   const message =
     typeof errorPayload?.error?.message === "string"
       ? errorPayload.error.message

src/lib/guardrails/visionBridgeHelpers.ts

@@ -222,7 +222,7 @@ const VISION_BRIDGE_UA_FETCH: typeof fetch = ((input: RequestInfo | URL, init?:
       "user-agent": "omniroute-vision-bridge",
       ...((init?.headers as Record<string, string> | undefined) ?? {}),
     },
-  })) as typeof fetch;
+  })) as unknown as typeof fetch;
 
 /**
  * Resolve every image part in the body to a base64 data URI when the target

src/lib/providers/mergeProviderModelListing.ts

@@ -19,7 +19,7 @@ export type ProviderListingModel = {
 
 export type MergeProviderModelListingInput = {
   providerId: string;
-  registryModels: Array<{ id: string; name?: string; [key: string]: unknown }>;
+  registryModels: Array<{ id: string; name?: string }>;
   syncedModels: Array<{ id: string; name?: string; [key: string]: unknown }>;
   customModels: Array<{ id: string; name?: string; source?: string; [key: string]: unknown }>;
   usesCuratedModelsOnly?: boolean;