fix(pty_terminal): use yield_now instead of sleep, revert temp CI

Replace disallowed std::thread::sleep with std::thread::yield_now
in the signal polling loop. Remove temporary 10x retry CI step
(all 10 retries passed, confirming stability).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: branchseer

.github/workflows/ci.yml

@@ -173,13 +173,6 @@ jobs:
           pnpm install
 
       - run: cargo test
-      # TEMPORARY: verify send_ctrl_c_interrupts_process stability (10 retries)
-      - name: Retry ctrl_c test 10 times
-        run: |
-          for i in $(seq 1 10); do
-            echo "--- Run $i/10 ---"
-            cargo test -p pty_terminal --test terminal -- send_ctrl_c_interrupts_process
-          done
 
   fmt:
     name: Format and Check Deps

crates/pty_terminal/tests/terminal.rs

@@ -309,7 +309,7 @@ fn send_ctrl_c_interrupts_process() {
                     stdout().flush().unwrap();
                     std::process::exit(0);
                 }
-                std::thread::sleep(std::time::Duration::from_millis(10));
+                std::thread::yield_now();
             }
         }