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/mutex_ns/mutex.rs

@@ -0,0 +1,127 @@
+#[doc = "Register `MUTEX[%s]` reader"]
+pub struct R(crate::R<MUTEX_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<MUTEX_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<MUTEX_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<MUTEX_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Register `MUTEX[%s]` writer"]
+pub struct W(crate::W<MUTEX_SPEC>);
+impl core::ops::Deref for W {
+    type Target = crate::W<MUTEX_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<MUTEX_SPEC>> for W {
+    #[inline(always)]
+    fn from(writer: crate::W<MUTEX_SPEC>) -> Self {
+        W(writer)
+    }
+}
+#[doc = "Field `MUTEX` reader - Mutex register n"]
+pub type MUTEX_R = crate::BitReader<MUTEX_A>;
+#[doc = "Mutex register n\n\nValue on reset: 0"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum MUTEX_A {
+    #[doc = "0: Mutex n is in unlocked state"]
+    UNLOCKED = 0,
+    #[doc = "1: Mutex n is in locked state"]
+    LOCKED = 1,
+}
+impl From<MUTEX_A> for bool {
+    #[inline(always)]
+    fn from(variant: MUTEX_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl MUTEX_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> MUTEX_A {
+        match self.bits {
+            false => MUTEX_A::UNLOCKED,
+            true => MUTEX_A::LOCKED,
+        }
+    }
+    #[doc = "Checks if the value of the field is `UNLOCKED`"]
+    #[inline(always)]
+    pub fn is_unlocked(&self) -> bool {
+        *self == MUTEX_A::UNLOCKED
+    }
+    #[doc = "Checks if the value of the field is `LOCKED`"]
+    #[inline(always)]
+    pub fn is_locked(&self) -> bool {
+        *self == MUTEX_A::LOCKED
+    }
+}
+#[doc = "Field `MUTEX` writer - Mutex register n"]
+pub type MUTEX_W<'a, const O: u8> = crate::BitWriter<'a, u32, MUTEX_SPEC, MUTEX_A, O>;
+impl<'a, const O: u8> MUTEX_W<'a, O> {
+    #[doc = "Mutex n is in unlocked state"]
+    #[inline(always)]
+    pub fn unlocked(self) -> &'a mut W {
+        self.variant(MUTEX_A::UNLOCKED)
+    }
+    #[doc = "Mutex n is in locked state"]
+    #[inline(always)]
+    pub fn locked(self) -> &'a mut W {
+        self.variant(MUTEX_A::LOCKED)
+    }
+}
+impl R {
+    #[doc = "Bit 0 - Mutex register n"]
+    #[inline(always)]
+    pub fn mutex(&self) -> MUTEX_R {
+        MUTEX_R::new((self.bits & 1) != 0)
+    }
+}
+impl W {
+    #[doc = "Bit 0 - Mutex register n"]
+    #[inline(always)]
+    pub fn mutex(&mut self) -> MUTEX_W<0> {
+        MUTEX_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 = "Description collection: Mutex register\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 [mutex](index.html) module"]
+pub struct MUTEX_SPEC;
+impl crate::RegisterSpec for MUTEX_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [mutex::R](R) reader structure"]
+impl crate::Readable for MUTEX_SPEC {
+    type Reader = R;
+}
+#[doc = "`write(|w| ..)` method takes [mutex::W](W) writer structure"]
+impl crate::Writable for MUTEX_SPEC {
+    type Writer = W;
+}
+#[doc = "`reset()` method sets MUTEX[%s]
+to value 0"]
+impl crate::Resettable for MUTEX_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0
+    }
+}