🤖 feat: Custom Endpoint Agents (experimental) (#4627)

* wip: first pass, custom endpoint agents

* chore: imports

* chore: consolidate exports

* fix: imports

* feat: convert message.content array to strings for legacy format handling (deepseek/groq)

* refactor: normalize ollama endpoint name

* refactor: update mocking in isDomainAllowed.spec.js

* refactor: update deepseekModels in tokens.js and tokens.spec.js

api/server/controllers/agents/client.js

@@ -13,6 +13,7 @@ const {
   VisionModes,
   openAISchema,
   EModelEndpoint,
+  KnownEndpoints,
   anthropicSchema,
   bedrockOutputParser,
   removeNullishValues,
@@ -25,6 +26,7 @@ const {
 const {
   formatMessage,
   formatAgentMessages,
+  formatContentStrings,
   createContextHandlers,
 } = require('~/app/clients/prompts');
 const { encodeAndFormat } = require('~/server/services/Files/images/encode');
@@ -44,6 +46,8 @@ const providerParsers = {
   [EModelEndpoint.bedrock]: bedrockOutputParser,
 };
 
+const legacyContentEndpoints = new Set([KnownEndpoints.groq, KnownEndpoints.deepseek]);
+
 class AgentClient extends BaseClient {
   constructor(options = {}) {
     super(null, options);
@@ -74,6 +78,7 @@ class AgentClient extends BaseClient {
     this.collectedUsage = collectedUsage;
     /** @type {ArtifactPromises} */
     this.artifactPromises = artifactPromises;
+    /** @type {AgentClientOptions} */
     this.options = Object.assign({ endpoint: options.endpoint }, clientOptions);
   }
 
@@ -478,6 +483,9 @@ class AgentClient extends BaseClient {
       this.run = run;
 
       const messages = formatAgentMessages(payload);
+      if (legacyContentEndpoints.has(this.options.agent.endpoint)) {
+        formatContentStrings(messages);
+      }
       await run.processStream({ messages }, config, {
         [Callback.TOOL_ERROR]: (graph, error, toolId) => {
           logger.error(