fix(cli): Increase Tokio thread stack size

Set runtime thread stacks to 16 MiB to avoid stack overflow in the
agent execution and configuration update path in debug builds.
The outer CLI thread's stack size does not apply to runtime threads.

Linux CI probes failed twice with the default stack and passed twice
with 16 MiB. Local cargo check --locked -p openbitfun-cli passes.

Author: wsp1911

src/apps/cli/src/main.rs

@@ -1714,6 +1714,9 @@ fn main() {
         .stack_size(16 * 1024 * 1024)
         .spawn(|| {
             let runtime = tokio::runtime::Builder::new_multi_thread()
+                // Agent execution can exceed Tokio's default stack in debug builds.
+                // Runtime threads do not inherit the outer thread's stack size.
+                .thread_stack_size(16 * 1024 * 1024)
                 .enable_all()
                 .build()
                 .expect("failed to build tokio runtime");