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/nrf9120-pac/src/clock_ns/intpend.rs

@@ -0,0 +1,115 @@
+#[doc = "Register `INTPEND` reader"]
+pub struct R(crate::R<INTPEND_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<INTPEND_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<INTPEND_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<INTPEND_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Field `HFCLKSTARTED` reader - Read pending status of interrupt for event HFCLKSTARTED"]
+pub type HFCLKSTARTED_R = crate::BitReader<HFCLKSTARTED_A>;
+#[doc = "Read pending status of interrupt for event HFCLKSTARTED\n\nValue on reset: 0"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum HFCLKSTARTED_A {
+    #[doc = "0: Read: Not pending"]
+    NOT_PENDING = 0,
+    #[doc = "1: Read: Pending"]
+    PENDING = 1,
+}
+impl From<HFCLKSTARTED_A> for bool {
+    #[inline(always)]
+    fn from(variant: HFCLKSTARTED_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl HFCLKSTARTED_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> HFCLKSTARTED_A {
+        match self.bits {
+            false => HFCLKSTARTED_A::NOT_PENDING,
+            true => HFCLKSTARTED_A::PENDING,
+        }
+    }
+    #[doc = "Checks if the value of the field is `NOT_PENDING`"]
+    #[inline(always)]
+    pub fn is_not_pending(&self) -> bool {
+        *self == HFCLKSTARTED_A::NOT_PENDING
+    }
+    #[doc = "Checks if the value of the field is `PENDING`"]
+    #[inline(always)]
+    pub fn is_pending(&self) -> bool {
+        *self == HFCLKSTARTED_A::PENDING
+    }
+}
+#[doc = "Field `LFCLKSTARTED` reader - Read pending status of interrupt for event LFCLKSTARTED"]
+pub type LFCLKSTARTED_R = crate::BitReader<LFCLKSTARTED_A>;
+#[doc = "Read pending status of interrupt for event LFCLKSTARTED\n\nValue on reset: 0"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum LFCLKSTARTED_A {
+    #[doc = "0: Read: Not pending"]
+    NOT_PENDING = 0,
+    #[doc = "1: Read: Pending"]
+    PENDING = 1,
+}
+impl From<LFCLKSTARTED_A> for bool {
+    #[inline(always)]
+    fn from(variant: LFCLKSTARTED_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl LFCLKSTARTED_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> LFCLKSTARTED_A {
+        match self.bits {
+            false => LFCLKSTARTED_A::NOT_PENDING,
+            true => LFCLKSTARTED_A::PENDING,
+        }
+    }
+    #[doc = "Checks if the value of the field is `NOT_PENDING`"]
+    #[inline(always)]
+    pub fn is_not_pending(&self) -> bool {
+        *self == LFCLKSTARTED_A::NOT_PENDING
+    }
+    #[doc = "Checks if the value of the field is `PENDING`"]
+    #[inline(always)]
+    pub fn is_pending(&self) -> bool {
+        *self == LFCLKSTARTED_A::PENDING
+    }
+}
+impl R {
+    #[doc = "Bit 0 - Read pending status of interrupt for event HFCLKSTARTED"]
+    #[inline(always)]
+    pub fn hfclkstarted(&self) -> HFCLKSTARTED_R {
+        HFCLKSTARTED_R::new((self.bits & 1) != 0)
+    }
+    #[doc = "Bit 1 - Read pending status of interrupt for event LFCLKSTARTED"]
+    #[inline(always)]
+    pub fn lfclkstarted(&self) -> LFCLKSTARTED_R {
+        LFCLKSTARTED_R::new(((self.bits >> 1) & 1) != 0)
+    }
+}
+#[doc = "Pending interrupts\n\nThis register you can [`read`](crate::generic::Reg::read). See [API](https://docs.rs/svd2rust/#read--modify--write-api).\n\nFor information about available fields see [intpend](index.html) module"]
+pub struct INTPEND_SPEC;
+impl crate::RegisterSpec for INTPEND_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [intpend::R](R) reader structure"]
+impl crate::Readable for INTPEND_SPEC {
+    type Reader = R;
+}
+#[doc = "`reset()` method sets INTPEND to value 0"]
+impl crate::Resettable for INTPEND_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0
+    }
+}