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/qspi_ns/xipen.rs

@@ -0,0 +1,126 @@
+#[doc = "Register `XIPEN` reader"]
+pub struct R(crate::R<XIPEN_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<XIPEN_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<XIPEN_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<XIPEN_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Register `XIPEN` writer"]
+pub struct W(crate::W<XIPEN_SPEC>);
+impl core::ops::Deref for W {
+    type Target = crate::W<XIPEN_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<XIPEN_SPEC>> for W {
+    #[inline(always)]
+    fn from(writer: crate::W<XIPEN_SPEC>) -> Self {
+        W(writer)
+    }
+}
+#[doc = "Field `XIPEN` reader - Enable XIP AHB Slave interface and access to XIP memory range"]
+pub type XIPEN_R = crate::BitReader<XIPEN_A>;
+#[doc = "Enable XIP AHB Slave interface and access to XIP memory range\n\nValue on reset: 1"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum XIPEN_A {
+    #[doc = "0: Disable XIP interface"]
+    DISABLE = 0,
+    #[doc = "1: Enable XIP interface"]
+    ENABLE = 1,
+}
+impl From<XIPEN_A> for bool {
+    #[inline(always)]
+    fn from(variant: XIPEN_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl XIPEN_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> XIPEN_A {
+        match self.bits {
+            false => XIPEN_A::DISABLE,
+            true => XIPEN_A::ENABLE,
+        }
+    }
+    #[doc = "Checks if the value of the field is `DISABLE`"]
+    #[inline(always)]
+    pub fn is_disable(&self) -> bool {
+        *self == XIPEN_A::DISABLE
+    }
+    #[doc = "Checks if the value of the field is `ENABLE`"]
+    #[inline(always)]
+    pub fn is_enable(&self) -> bool {
+        *self == XIPEN_A::ENABLE
+    }
+}
+#[doc = "Field `XIPEN` writer - Enable XIP AHB Slave interface and access to XIP memory range"]
+pub type XIPEN_W<'a, const O: u8> = crate::BitWriter<'a, u32, XIPEN_SPEC, XIPEN_A, O>;
+impl<'a, const O: u8> XIPEN_W<'a, O> {
+    #[doc = "Disable XIP interface"]
+    #[inline(always)]
+    pub fn disable(self) -> &'a mut W {
+        self.variant(XIPEN_A::DISABLE)
+    }
+    #[doc = "Enable XIP interface"]
+    #[inline(always)]
+    pub fn enable(self) -> &'a mut W {
+        self.variant(XIPEN_A::ENABLE)
+    }
+}
+impl R {
+    #[doc = "Bit 0 - Enable XIP AHB Slave interface and access to XIP memory range"]
+    #[inline(always)]
+    pub fn xipen(&self) -> XIPEN_R {
+        XIPEN_R::new((self.bits & 1) != 0)
+    }
+}
+impl W {
+    #[doc = "Bit 0 - Enable XIP AHB Slave interface and access to XIP memory range"]
+    #[inline(always)]
+    pub fn xipen(&mut self) -> XIPEN_W<0> {
+        XIPEN_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 = "Enable Execute in Place operation.\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 [xipen](index.html) module"]
+pub struct XIPEN_SPEC;
+impl crate::RegisterSpec for XIPEN_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [xipen::R](R) reader structure"]
+impl crate::Readable for XIPEN_SPEC {
+    type Reader = R;
+}
+#[doc = "`write(|w| ..)` method takes [xipen::W](W) writer structure"]
+impl crate::Writable for XIPEN_SPEC {
+    type Writer = W;
+}
+#[doc = "`reset()` method sets XIPEN to value 0x01"]
+impl crate::Resettable for XIPEN_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0x01
+    }
+}