fix(config): add missing comment field to BindingsSchema

Strict validation (added in d1e9490f9) rejects the legitimate 'comment'
field on bindings. This field is used for annotations in config files.

Changes:
- BindingsSchema: added comment: z.string().optional()
- AgentBinding type: added comment?: string

Fixes #23385

src/config/types.agents.ts

@@ -72,6 +72,7 @@ export type AgentsConfig = {
 
 export type AgentBinding = {
   agentId: string;
+  comment?: string;
   match: {
     channel: string;
     accountId?: string;

src/config/zod-schema.agents.ts

@@ -16,6 +16,7 @@ export const BindingsSchema = z
     z
       .object({
         agentId: z.string(),
+        comment: z.string().optional(),
         match: z
           .object({
             channel: z.string(),