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.

server/handlers/deploy.js

@@ -26,13 +26,52 @@ export function registerDeployHandlers(session) {
     args.image = image
 
     const existingContainers = await docker.listContainers({ all: true })
-    if (existingContainers.some((c) => c.Names.includes(`/${args.containerName}`))) {
-      throw formatDeployError(
-        new Error(
-          `Conflict. The container name "/${args.containerName}" is already in use by container. You have to remove (or rename) that container to be able to reuse that name.`
-        ),
-        { stage: 'create', containerName: args.containerName, image: args.image }
-      )
+    const existing = existingContainers.find((c) =>
+      (c.Names || []).some((n) => {
+        const bare = String(n || '').replace(/^\//, '')
+        return bare === args.containerName || n === `/${args.containerName}`
+      })
+    )
+
+    // Portainer-style replace: stop+remove the name holder, then create new
+    if (existing) {
+      if (args.replace === true) {
+        logger.info('Replacing existing container', {
+          name: args.containerName,
+          id: String(existing.Id || '').slice(0, 12),
+          state: existing.State,
+        })
+        const old = docker.getContainer(existing.Id)
+        try {
+          await old.stop({ t: 10 })
+        } catch {
+          // already stopped / gone
+        }
+        try {
+          await old.remove({ force: true })
+        } catch (rmErr) {
+          throw formatDeployError(rmErr, {
+            stage: 'replace',
+            containerName: args.containerName,
+            image: args.image,
+          })
+        }
+      } else {
+        const err = new Error(
+          `A container named "${args.containerName}" already exists` +
+            (existing.State ? ` (${existing.State})` : '') +
+            (existing.Image ? ` · image ${existing.Image}` : '') +
+            '. Deploying will stop and remove it, then create a new container with your settings.'
+        )
+        err.code = 'CONTAINER_NAME_CONFLICT'
+        err.existing = {
+          id: existing.Id,
+          name: args.containerName,
+          state: existing.State || 'unknown',
+          image: existing.Image || '',
+        }
+        throw err
+      }
     }
 
     // Skip pull when client already pulled (job stepper) unless force
@@ -278,13 +317,18 @@ export function registerDeployHandlers(session) {
     logger.info('Container deployed successfully', {
       name: args.containerName,
       image: args.image,
+      replaced: args.replace === true,
     })
 
     await broadcastContainers()
     return {
       success: true,
-      message: `Container "${args.containerName}" deployed successfully from image "${args.image}"`,
+      message:
+        args.replace === true
+          ? `Container "${args.containerName}" replaced successfully from image "${args.image}"`
+          : `Container "${args.containerName}" deployed successfully from image "${args.image}"`,
       id: container.id,
+      replaced: args.replace === true,
     }
   })
 }