fix: address reviewer feedback — rename scroll field to bool, relocate static, drop env var

- Rename `ui_scroll_tick_count: u64` → `should_text_scroll: bool` across all 33
  call sites; `on_ui_scroll_tick` now assigns true/false instead of 0/1
- Remove two now-redundant comments from `test_on_ui_scroll_tick`
- Move `WHITESPACE_RE` static declaration below module imports in network/mod.rs
- Remove `MANAGARR_TICK_RATE_MS` env var and its parsing helpers; `recv()`-based
  blocking already brings idle CPU to near-0, and tuning tick rate silently
  stretches the poll cadence — keep `DEFAULT_TICK_RATE_MS` const only

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01C3FpbniZme9mJqgFkMVowz

src/event/input_event.rs

@@ -1,5 +1,4 @@
 use anyhow::Result;
-use std::env;
 use std::sync::mpsc;
 use std::sync::mpsc::Receiver;
 use std::thread;
@@ -21,22 +20,10 @@ pub struct Events {
 
 const DEFAULT_TICK_RATE_MS: u64 = 50;
 
-fn configured_tick_rate_ms_from(raw: Option<&str>) -> u64 {
-  raw
-    .and_then(|value| value.parse::<u64>().ok())
-    .filter(|ms| *ms > 0)
-    .unwrap_or(DEFAULT_TICK_RATE_MS)
-}
-
-fn configured_tick_rate_ms() -> u64 {
-  let raw = env::var("MANAGARR_TICK_RATE_MS").ok();
-  configured_tick_rate_ms_from(raw.as_deref())
-}
-
 impl Events {
   pub fn new() -> Self {
     let (tx, rx) = mpsc::channel();
-    let tick_rate: Duration = Duration::from_millis(configured_tick_rate_ms());
+    let tick_rate: Duration = Duration::from_millis(DEFAULT_TICK_RATE_MS);
 
     thread::spawn(move || {
       let mut last_tick = Instant::now();
@@ -80,16 +67,5 @@ mod tests {
   #[test]
   fn defaults_to_original_tick_rate() {
     assert_eq!(DEFAULT_TICK_RATE_MS, 50);
-    assert_eq!(configured_tick_rate_ms_from(None), 50);
-  }
-
-  #[test]
-  fn parses_positive_tick_rates_and_rejects_invalid_values() {
-    assert_eq!(configured_tick_rate_ms_from(Some("250")), 250);
-    assert_eq!(configured_tick_rate_ms_from(Some("0")), DEFAULT_TICK_RATE_MS);
-    assert_eq!(
-      configured_tick_rate_ms_from(Some("abc")),
-      DEFAULT_TICK_RATE_MS
-    );
   }
 }