fix(omp): accept all command source types in slash command schema (#2175)

OmpRpcSlashCommandSchema had a strict source enum
['extension', 'prompt', 'skill', 'builtin'] that rejected omp
commands with source 'custom' or 'file'. When omp reported any such
command, the entire get_available_commands response failed Zod
validation and listCommands returned an empty array — so the Paseo
autocomplete only showed /exit and /clear instead of all omp commands.

Relax source to z.string().optional(), matching the already-permissive
OmpAvailableCommandSchema used for the available_commands_update event.

packages/server/src/server/agent/providers/omp/rpc-types.ts

@@ -149,7 +149,7 @@ export const OmpRpcSlashCommandSchema = z
   .object({
     name: z.string(),
     description: z.string().optional(),
-    source: z.enum(["extension", "prompt", "skill", "builtin"]),
+    source: z.string().optional(),
     sourceInfo: z.record(z.string(), z.unknown()).optional(),
     input: z.object({ hint: z.string().optional() }).passthrough().nullable().optional(),
   })