refactor: rename project to DongLoRa

Rebrand from lora-dongle to DongLoRa (portmanteau of dongle + LoRa).
Lowercase donglora in Cargo package name, firmware filenames, and code.
Splash screen shows "DongLoRa" in 9x15 bold.

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

src/display/render.rs

@@ -38,7 +38,7 @@ pub fn splash(
     let sub_style = MonoTextStyle::new(&FONT_6X10, BinaryColor::On);
 
     // Title centered vertically and horizontally
-    Text::with_alignment("LoRa Dongle", Point::new(W / 2, 24), title_style, Alignment::Center)
+    Text::with_alignment("DongLoRa", Point::new(W / 2, 24), title_style, Alignment::Center)
         .draw(target)
         .ok();