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/nrf52840-pac/src/nfct/nfcid1_last.rs

@@ -0,0 +1,122 @@
+#[doc = "Register `NFCID1_LAST` reader"]
+pub struct R(crate::R<NFCID1_LAST_SPEC>);
+impl core::ops::Deref for R {
+    type Target = crate::R<NFCID1_LAST_SPEC>;
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+impl From<crate::R<NFCID1_LAST_SPEC>> for R {
+    #[inline(always)]
+    fn from(reader: crate::R<NFCID1_LAST_SPEC>) -> Self {
+        R(reader)
+    }
+}
+#[doc = "Register `NFCID1_LAST` writer"]
+pub struct W(crate::W<NFCID1_LAST_SPEC>);
+impl core::ops::Deref for W {
+    type Target = crate::W<NFCID1_LAST_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<NFCID1_LAST_SPEC>> for W {
+    #[inline(always)]
+    fn from(writer: crate::W<NFCID1_LAST_SPEC>) -> Self {
+        W(writer)
+    }
+}
+#[doc = "Field `NFCID1_Z` reader - NFCID1 byte Z (very last byte sent)"]
+pub type NFCID1_Z_R = crate::FieldReader<u8, u8>;
+#[doc = "Field `NFCID1_Z` writer - NFCID1 byte Z (very last byte sent)"]
+pub type NFCID1_Z_W<'a, const O: u8> = crate::FieldWriter<'a, u32, NFCID1_LAST_SPEC, u8, u8, 8, O>;
+#[doc = "Field `NFCID1_Y` reader - NFCID1 byte Y"]
+pub type NFCID1_Y_R = crate::FieldReader<u8, u8>;
+#[doc = "Field `NFCID1_Y` writer - NFCID1 byte Y"]
+pub type NFCID1_Y_W<'a, const O: u8> = crate::FieldWriter<'a, u32, NFCID1_LAST_SPEC, u8, u8, 8, O>;
+#[doc = "Field `NFCID1_X` reader - NFCID1 byte X"]
+pub type NFCID1_X_R = crate::FieldReader<u8, u8>;
+#[doc = "Field `NFCID1_X` writer - NFCID1 byte X"]
+pub type NFCID1_X_W<'a, const O: u8> = crate::FieldWriter<'a, u32, NFCID1_LAST_SPEC, u8, u8, 8, O>;
+#[doc = "Field `NFCID1_W` reader - NFCID1 byte W"]
+pub type NFCID1_W_R = crate::FieldReader<u8, u8>;
+#[doc = "Field `NFCID1_W` writer - NFCID1 byte W"]
+pub type NFCID1_W_W<'a, const O: u8> = crate::FieldWriter<'a, u32, NFCID1_LAST_SPEC, u8, u8, 8, O>;
+impl R {
+    #[doc = "Bits 0:7 - NFCID1 byte Z (very last byte sent)"]
+    #[inline(always)]
+    pub fn nfcid1_z(&self) -> NFCID1_Z_R {
+        NFCID1_Z_R::new((self.bits & 0xff) as u8)
+    }
+    #[doc = "Bits 8:15 - NFCID1 byte Y"]
+    #[inline(always)]
+    pub fn nfcid1_y(&self) -> NFCID1_Y_R {
+        NFCID1_Y_R::new(((self.bits >> 8) & 0xff) as u8)
+    }
+    #[doc = "Bits 16:23 - NFCID1 byte X"]
+    #[inline(always)]
+    pub fn nfcid1_x(&self) -> NFCID1_X_R {
+        NFCID1_X_R::new(((self.bits >> 16) & 0xff) as u8)
+    }
+    #[doc = "Bits 24:31 - NFCID1 byte W"]
+    #[inline(always)]
+    pub fn nfcid1_w(&self) -> NFCID1_W_R {
+        NFCID1_W_R::new(((self.bits >> 24) & 0xff) as u8)
+    }
+}
+impl W {
+    #[doc = "Bits 0:7 - NFCID1 byte Z (very last byte sent)"]
+    #[inline(always)]
+    pub fn nfcid1_z(&mut self) -> NFCID1_Z_W<0> {
+        NFCID1_Z_W::new(self)
+    }
+    #[doc = "Bits 8:15 - NFCID1 byte Y"]
+    #[inline(always)]
+    pub fn nfcid1_y(&mut self) -> NFCID1_Y_W<8> {
+        NFCID1_Y_W::new(self)
+    }
+    #[doc = "Bits 16:23 - NFCID1 byte X"]
+    #[inline(always)]
+    pub fn nfcid1_x(&mut self) -> NFCID1_X_W<16> {
+        NFCID1_X_W::new(self)
+    }
+    #[doc = "Bits 24:31 - NFCID1 byte W"]
+    #[inline(always)]
+    pub fn nfcid1_w(&mut self) -> NFCID1_W_W<24> {
+        NFCID1_W_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 = "Last NFCID1 part (4, 7 or 10 bytes ID)\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 [nfcid1_last](index.html) module"]
+pub struct NFCID1_LAST_SPEC;
+impl crate::RegisterSpec for NFCID1_LAST_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [nfcid1_last::R](R) reader structure"]
+impl crate::Readable for NFCID1_LAST_SPEC {
+    type Reader = R;
+}
+#[doc = "`write(|w| ..)` method takes [nfcid1_last::W](W) writer structure"]
+impl crate::Writable for NFCID1_LAST_SPEC {
+    type Writer = W;
+}
+#[doc = "`reset()` method sets NFCID1_LAST to value 0x6363"]
+impl crate::Resettable for NFCID1_LAST_SPEC {
+    #[inline(always)]
+    fn reset_value() -> Self::Ux {
+        0x6363
+    }
+}