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/network/mod.rs

@@ -6,8 +6,6 @@ use async_trait::async_trait;
 use lidarr_network::LidarrEvent;
 use log::{debug, error, warn};
 use regex::Regex;
-
-static WHITESPACE_RE: OnceLock<Regex> = OnceLock::new();
 use reqwest::{Client, RequestBuilder};
 use serde::Serialize;
 use serde::de::DeserializeOwned;
@@ -35,6 +33,8 @@ mod network_tests;
 #[cfg(test)]
 pub mod servarr_test_utils;
 
+static WHITESPACE_RE: OnceLock<Regex> = OnceLock::new();
+
 #[cfg_attr(test, automock)]
 #[async_trait]
 pub trait NetworkTrait {