fix: replace print_and_exit() with Err(anyhow!(...))

This fixes a deadlock in tui mode, because of tokio task error propagation. Can be
reproduced by listing an extension under a runtime, but not defining in the extensions:
section.

Flow chain before fix:
- spawned tokio task (ext build) hits stamp validation failure
- calls print_and_exit() → renderer.shutdown()
- shutdown() busy-waits with std::thread::sleep(5ms) for the render loop to stop
- std::thread::sleep() blocks the tokio thread, preventing the render loop task from running
- render loop never sets loop_stopped = true
- deadlock — shutdown() spins forever

Signed-off-by: Beniamin Sandu <b.sandu@peridio.com>

Author: bsandu-peridio

src/commands/ext/build.rs

@@ -191,9 +191,9 @@ impl ExtBuildCommand {
             );
 
             if !validation.is_satisfied() {
-                validation
-                    .into_error(&format!("Cannot build extension '{}'", self.extension))
-                    .print_and_exit();
+                let err =
+                    validation.into_error(&format!("Cannot build extension '{}'", self.extension));
+                return Err(anyhow::anyhow!("{err}"));
             }
         }