scxtop: Refactor network rendering into separate module (Phase 3)

Extract all network rendering logic (~687 lines) from app.rs into a new
NetworkRenderer module in src/render/network.rs. This includes:

- Full network view with interface table and traffic charts
- Network summary for default view (top 5 interfaces)
- Historical traffic visualization (bytes and packets)
- Dual-axis mirrored charts (RX negative, TX positive)
- Delta calculation for per-second rates
- Comprehensive error handling and edge cases

Add extensive test coverage with 13 tests covering:
- Basic rendering, localization, themes
- Edge cases: no interfaces, zero/high traffic, many interfaces
- Small terminal compatibility
- Multiple tick rates

Signed-off-by: Daniel Hodges <[email protected]>

Author: hodgesds

tools/scxtop/src/app.rs

@@ -20,7 +20,7 @@ pub mod layered_util;
 mod llc_data;
 pub mod mangoapp;
 mod mem_stats;
-mod network_stats;
+pub mod network_stats;
 mod node_data;
 mod perfetto_trace;
 mod power_data;

tools/scxtop/src/lib.rs

@@ -14,10 +14,8 @@ use anyhow::Result;
 use ratatui::layout::{Alignment, Constraint, Layout};
 use ratatui::symbols::line::THICK;
 use ratatui::text::{Line, Span};
-use ratatui::widgets::{
-    Block, BorderType, Cell, LineGauge, Row, Table,
-};
-use ratatui::{Frame, layout::Rect};
+use ratatui::widgets::{Block, BorderType, Cell, LineGauge, Row, Table};
+use ratatui::{layout::Rect, Frame};
 
 /// Renderer for memory views
 pub struct MemoryRenderer;
@@ -219,7 +217,9 @@ impl MemoryRenderer {
             Line::from(vec![
                 Span::styled(
                     &memory_key,
-                    theme.title_style().add_modifier(ratatui::style::Modifier::BOLD),
+                    theme
+                        .title_style()
+                        .add_modifier(ratatui::style::Modifier::BOLD),
                 ),
                 Span::styled("emory Statistics", theme.text_color()),
             ])

tools/scxtop/src/render/memory.rs

@@ -7,6 +7,9 @@
 pub mod process;
 // Memory rendering
 pub mod memory;
+// Network rendering
+pub mod network;
 
-pub use process::ProcessRenderer;
 pub use memory::MemoryRenderer;
+pub use network::NetworkRenderer;
+pub use process::ProcessRenderer;