feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

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

vendor/nrf5340-app-pac/src/spis0_ns/orc.rs

@@ -0,0 +1,80 @@
+#[doc = "Register `ORC` reader"]
+pub struct R(crate::R<ORC_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<ORC_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<ORC_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<ORC_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Register `ORC` writer"]
+pub struct W(crate::W<ORC_SPEC>);
+impl core::ops::Deref for W {
+    type Target = crate::W<ORC_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl core::ops::DerefMut for W {
+    #[inline(always)]
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+impl From<crate::W<ORC_SPEC>> for W {
+    #[inline(always)]
+    fn from(writer: crate::W<ORC_SPEC>) -> Self {
+        W(writer)
+    }
+}
+#[doc = "Field `ORC` reader - Over-read character. Character clocked out after an over-read of the transmit buffer."]
+pub type ORC_R = crate::FieldReader<u8, u8>;
+#[doc = "Field `ORC` writer - Over-read character. Character clocked out after an over-read of the transmit buffer."]
+pub type ORC_W<'a, const O: u8> = crate::FieldWriter<'a, u32, ORC_SPEC, u8, u8, 8, O>;
+impl R {
+    #[doc = "Bits 0:7 - Over-read character. Character clocked out after an over-read of the transmit buffer."]
+    #[inline(always)]
+    pub fn orc(&self) -> ORC_R {
+        ORC_R::new((self.bits & 0xff) as u8)
+    }
+}
+impl W {
+    #[doc = "Bits 0:7 - Over-read character. Character clocked out after an over-read of the transmit buffer."]
+    #[inline(always)]
+    pub fn orc(&mut self) -> ORC_W<0> {
+        ORC_W::new(self)
+    }
+    #[doc = "Writes raw bits to the register."]
+    #[inline(always)]
+    pub unsafe fn bits(&mut self, bits: u32) -> &mut Self {
+        self.0.bits(bits);
+        self
+    }
+}
+#[doc = "Over-read character\n\nThis register you can [`read`](crate::generic::Reg::read), [`write_with_zero`](crate::generic::Reg::write_with_zero), [`reset`](crate::generic::Reg::reset), [`write`](crate::generic::Reg::write), [`modify`](crate::generic::Reg::modify). See [API](https://docs.rs/svd2rust/#read--modify--write-api).\n\nFor information about available fields see [orc](index.html) module"]
+pub struct ORC_SPEC;
+impl crate::RegisterSpec for ORC_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [orc::R](R) reader structure"]
+impl crate::Readable for ORC_SPEC {
+    type Reader = R;
+}
+#[doc = "`write(|w| ..)` method takes [orc::W](W) writer structure"]
+impl crate::Writable for ORC_SPEC {
+    type Writer = W;
+}
+#[doc = "`reset()` method sets ORC to value 0"]
+impl crate::Resettable for ORC_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0
+    }
+}