fix(cli): skip local agent validation in attach mode

When using `opencode run --attach` with the `--agent` flag, the CLI
would crash with "No context found for instance" because Agent.get()
requires the Instance context that is only available after bootstrap().

In attach mode, bootstrap() is never called since we're connecting to
a remote server. This fix skips local agent validation in attach mode,
allowing the remote server to handle agent validation instead.

Fixes anomalyco#6489 anomalyco#8094

Co-Authored-By: Claude <[email protected]>

Author: zerone0x

packages/opencode/src/cli/cmd/run.ts

@@ -231,6 +231,8 @@ export const RunCommand = cmd({
       // Validate agent if specified
       const resolvedAgent = await (async () => {
         if (!args.agent) return undefined
+        // Skip local agent validation in attach mode - the remote server handles it
+        if (args.attach) return args.agent
         const agent = await Agent.get(args.agent)
         if (!agent) {
           UI.println(