fix: PTY crash — use std:🧵:spawn instead of tokio::spawn_blocking

tokio::task::spawn_blocking panics when called without a tokio runtime
context. Sync Tauri command handlers may not have one. The PTY reader
loop is long-lived anyway — std:🧵:spawn is more correct for
persistent blocking I/O and doesn't require a runtime guard.

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

src-tauri/src/pty/mod.rs

@@ -112,11 +112,13 @@ impl PtyService {
 
         self.sessions.insert(session_id.clone(), session);
 
-        // Output reader loop — runs in a blocking thread because
-        // portable-pty's reader is synchronous (std::io::Read).
+        // Output reader loop — runs in a dedicated OS thread because
+        // portable-pty's reader is synchronous (std::io::Read) and
+        // long-lived. Using std::thread::spawn avoids requiring a
+        // tokio runtime context (sync Tauri commands may not have one).
         let sid = session_id.clone();
         let app = app_handle;
-        tokio::task::spawn_blocking(move || {
+        std::thread::spawn(move || {
             let mut reader = std::io::BufReader::new(reader);
             let mut buf = [0u8; 4096];
             loop {