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/status.rs

@@ -0,0 +1,122 @@
+#[doc = "Register `STATUS` reader"]
+pub struct R(crate::R<STATUS_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<STATUS_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<STATUS_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<STATUS_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Field `DPM` reader - Deep power-down mode (DPM) status of external flash."]
+pub type DPM_R = crate::BitReader<DPM_A>;
+#[doc = "Deep power-down mode (DPM) status of external flash.\n\nValue on reset: 0"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum DPM_A {
+    #[doc = "0: External flash is not in DPM."]
+    DISABLED = 0,
+    #[doc = "1: External flash is in DPM."]
+    ENABLED = 1,
+}
+impl From<DPM_A> for bool {
+    #[inline(always)]
+    fn from(variant: DPM_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl DPM_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> DPM_A {
+        match self.bits {
+            false => DPM_A::DISABLED,
+            true => DPM_A::ENABLED,
+        }
+    }
+    #[doc = "Checks if the value of the field is `DISABLED`"]
+    #[inline(always)]
+    pub fn is_disabled(&self) -> bool {
+        *self == DPM_A::DISABLED
+    }
+    #[doc = "Checks if the value of the field is `ENABLED`"]
+    #[inline(always)]
+    pub fn is_enabled(&self) -> bool {
+        *self == DPM_A::ENABLED
+    }
+}
+#[doc = "Field `READY` reader - Ready status."]
+pub type READY_R = crate::BitReader<READY_A>;
+#[doc = "Ready status.\n\nValue on reset: 0"]
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum READY_A {
+    #[doc = "1: QSPI peripheral is ready. It is allowed to trigger new tasks, writing custom instructions or enter/exit DPM."]
+    READY = 1,
+    #[doc = "0: QSPI peripheral is busy. It is not allowed to trigger any new tasks, writing custom instructions or enter/exit DPM."]
+    BUSY = 0,
+}
+impl From<READY_A> for bool {
+    #[inline(always)]
+    fn from(variant: READY_A) -> Self {
+        variant as u8 != 0
+    }
+}
+impl READY_R {
+    #[doc = "Get enumerated values variant"]
+    #[inline(always)]
+    pub fn variant(&self) -> READY_A {
+        match self.bits {
+            true => READY_A::READY,
+            false => READY_A::BUSY,
+        }
+    }
+    #[doc = "Checks if the value of the field is `READY`"]
+    #[inline(always)]
+    pub fn is_ready(&self) -> bool {
+        *self == READY_A::READY
+    }
+    #[doc = "Checks if the value of the field is `BUSY`"]
+    #[inline(always)]
+    pub fn is_busy(&self) -> bool {
+        *self == READY_A::BUSY
+    }
+}
+#[doc = "Field `SREG` reader - Value of external flash device Status Register. When the external flash has two bytes status register this field includes the value of the low byte."]
+pub type SREG_R = crate::FieldReader<u8, u8>;
+impl R {
+    #[doc = "Bit 2 - Deep power-down mode (DPM) status of external flash."]
+    #[inline(always)]
+    pub fn dpm(&self) -> DPM_R {
+        DPM_R::new(((self.bits >> 2) & 1) != 0)
+    }
+    #[doc = "Bit 3 - Ready status."]
+    #[inline(always)]
+    pub fn ready(&self) -> READY_R {
+        READY_R::new(((self.bits >> 3) & 1) != 0)
+    }
+    #[doc = "Bits 24:31 - Value of external flash device Status Register. When the external flash has two bytes status register this field includes the value of the low byte."]
+    #[inline(always)]
+    pub fn sreg(&self) -> SREG_R {
+        SREG_R::new(((self.bits >> 24) & 0xff) as u8)
+    }
+}
+#[doc = "Status register.\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 [status](index.html) module"]
+pub struct STATUS_SPEC;
+impl crate::RegisterSpec for STATUS_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [status::R](R) reader structure"]
+impl crate::Readable for STATUS_SPEC {
+    type Reader = R;
+}
+#[doc = "`reset()` method sets STATUS to value 0"]
+impl crate::Resettable for STATUS_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0
+    }
+}