fix: resolve 422 from Replicate + add local Cog Docker mode

- replicate-translate: parse owner/model:hash correctly — extract only
  the hash portion for the version field, and use the model endpoint
  (POST /v1/models/{owner}/{model}/predictions) which avoids 422
  'Invalid version' errors when sending the full owner/model:hash string.

- Add local Cog mode: when replicateMode="local", calls the local Docker
  container directly (no Replicate API key needed), default endpoint
  http://localhost:5030/predictions (host port 5030 → container port 5000).

- settings-store: add replicateMode ("cloud"|"local") and localEndpoint
  fields with env var fallbacks REPLICATE_MODE and LOCAL_MODEL_ENDPOINT.

- admin panel: Radio selector for Cloud vs Local mode; shows docker run
  command snippet and local endpoint URL field when local is selected;
  hides Replicate API token field in local mode (not needed).

Local model startup:
  docker run -d -p 5030:5000 \
    r8.im/jigsawstack/text-translate@sha256:454df4c...

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pages/api/admin/settings.ts

@@ -18,6 +18,8 @@ const handler: NextApiHandler = async (req, res) => {
             jigsawApiKey,
             modelVersion,
             replicateEnabled,
+            replicateMode,
+            localEndpoint,
             newPassword
         } = req.body ?? {};
 
@@ -26,6 +28,8 @@ const handler: NextApiHandler = async (req, res) => {
         if (jigsawApiKey !== undefined) updates.jigsawApiKey = jigsawApiKey;
         if (modelVersion !== undefined) updates.modelVersion = modelVersion;
         if (replicateEnabled !== undefined) updates.replicateEnabled = Boolean(replicateEnabled);
+        if (replicateMode === "cloud" || replicateMode === "local") updates.replicateMode = replicateMode;
+        if (localEndpoint !== undefined) updates.localEndpoint = localEndpoint;
         if (newPassword && typeof newPassword === "string" && newPassword.length >= 6) {
             updates.adminPasswordHash = newPassword;
         }