Add Portainer-style container name replace on deploy.

When deploying a container whose name already exists, prompt to Replace
(stop and remove the old container) or Cancel. Server accepts replace:true
to perform the swap; clients pre-check names and retry on conflict races.

client/errors.js

@@ -24,6 +24,12 @@ const CODE_MAP = {
       'A name or port is already in use. Rename the container, change the host port, or remove the existing resource.',
     severity: 'warning',
   },
+  CONTAINER_NAME_CONFLICT: {
+    title: 'Container name already in use',
+    recovery:
+      'Choose Replace to stop and remove the existing container, then deploy with your new settings — or pick a different name.',
+    severity: 'warning',
+  },
   DOCKER_ERROR: {
     title: 'Docker engine error',
     recovery: 'Read the error detail below, fix the configuration, and retry deploy.',
@@ -243,12 +249,20 @@ function classifyDockerMessage(message, method) {
       severity: 'warning',
     }
   }
-  if (/container name|already in use by container|name .* already/i.test(lower) && /use|conflict|taken/i.test(lower)) {
+  if (
+    err?.code === 'CONTAINER_NAME_CONFLICT' ||
+    (/container name|already in use by container|name .* already|already exists/i.test(lower) &&
+      /use|conflict|taken|exists|replace/i.test(lower))
+  ) {
     return {
-      code: 'DOCKER_CONFLICT',
+      code:
+        err?.code === 'CONTAINER_NAME_CONFLICT'
+          ? 'CONTAINER_NAME_CONFLICT'
+          : 'DOCKER_CONFLICT',
       title: 'Container name already taken',
       message: m,
-      recovery: 'Choose a different name, or remove/rename the existing container first.',
+      recovery:
+        'Choose Replace when prompted to stop and remove the existing container, or pick a different name.',
       severity: 'warning',
     }
   }