fix(setup): drain stale keypresses between TUI screen transitions (#186)

* fix(setup): drain stale keypresses between TUI screen transitions

The picker's vim-style j/k navigation can leave buffered keypresses in
crossterm's event queue that leak into the next input field, corrupting
pre-populated values like client_id.

* refactor: extract drain logic into helper, add changeset

.changeset/drain-stale-keypresses.md

@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+fix(setup): drain stale keypresses between TUI screen transitions

src/setup_tui.rs

@@ -448,6 +448,15 @@ fn run_picker_loop(
     }
 }
 
+/// Drains any queued crossterm events to prevent stale keypresses from leaking
+/// between TUI interactions.
+fn drain_pending_events() -> std::io::Result<()> {
+    while crossterm::event::poll(std::time::Duration::ZERO)? {
+        let _ = event::read()?;
+    }
+    Ok(())
+}
+
 // ── Setup Wizard (unified TUI session) ──────────────────────────
 
 /// Status of a single setup step.
@@ -536,6 +545,7 @@ impl SetupWizard {
         multiselect: bool,
     ) -> std::io::Result<PickerResult> {
         let mut picker = PickerState::new(title, help_text, items, multiselect);
+        drain_pending_events()?;
         loop {
             let steps_snapshot = self.steps.clone();
             let msg = self.message.clone();
@@ -598,6 +608,7 @@ impl SetupWizard {
         initial: Option<&str>,
     ) -> std::io::Result<InputResult> {
         let mut input = InputState::new(title, help_text, initial);
+        drain_pending_events()?;
         loop {
             let steps_snapshot = self.steps.clone();
             let msg = self.message.clone();