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/esp32s3/src/extmem/cache_mmu_owner.rs

@@ -0,0 +1,47 @@
+#[doc = "Register `CACHE_MMU_OWNER` reader"]
+pub type R = crate::R<CACHE_MMU_OWNER_SPEC>;
+#[doc = "Register `CACHE_MMU_OWNER` writer"]
+pub type W = crate::W<CACHE_MMU_OWNER_SPEC>;
+#[doc = "Field `CACHE_MMU_OWNER` reader - The bits are used to specify the owner of MMU.bit0: icache, bit1: dcache, bit2: dma, bit3: reserved."]
+pub type CACHE_MMU_OWNER_R = crate::FieldReader<u32>;
+#[doc = "Field `CACHE_MMU_OWNER` writer - The bits are used to specify the owner of MMU.bit0: icache, bit1: dcache, bit2: dma, bit3: reserved."]
+pub type CACHE_MMU_OWNER_W<'a, REG> = crate::FieldWriter<'a, REG, 24, u32>;
+impl R {
+    #[doc = "Bits 0:23 - The bits are used to specify the owner of MMU.bit0: icache, bit1: dcache, bit2: dma, bit3: reserved."]
+    #[inline(always)]
+    pub fn cache_mmu_owner(&self) -> CACHE_MMU_OWNER_R {
+        CACHE_MMU_OWNER_R::new(self.bits & 0x00ff_ffff)
+    }
+}
+#[cfg(feature = "impl-register-debug")]
+impl core::fmt::Debug for R {
+    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+        f.debug_struct("CACHE_MMU_OWNER")
+            .field("cache_mmu_owner", &self.cache_mmu_owner())
+            .finish()
+    }
+}
+impl W {
+    #[doc = "Bits 0:23 - The bits are used to specify the owner of MMU.bit0: icache, bit1: dcache, bit2: dma, bit3: reserved."]
+    #[inline(always)]
+    pub fn cache_mmu_owner(&mut self) -> CACHE_MMU_OWNER_W<CACHE_MMU_OWNER_SPEC> {
+        CACHE_MMU_OWNER_W::new(self, 0)
+    }
+}
+#[doc = "******* Description ***********\n\nYou can [`read`](crate::Reg::read) this register and get [`cache_mmu_owner::R`](R). You can [`reset`](crate::Reg::reset), [`write`](crate::Reg::write), [`write_with_zero`](crate::Reg::write_with_zero) this register using [`cache_mmu_owner::W`](W). You can also [`modify`](crate::Reg::modify) this register. See [API](https://docs.rs/svd2rust/#read--modify--write-api)."]
+pub struct CACHE_MMU_OWNER_SPEC;
+impl crate::RegisterSpec for CACHE_MMU_OWNER_SPEC {
+    type Ux = u32;
+}
+#[doc = "`read()` method returns [`cache_mmu_owner::R`](R) reader structure"]
+impl crate::Readable for CACHE_MMU_OWNER_SPEC {}
+#[doc = "`write(|w| ..)` method takes [`cache_mmu_owner::W`](W) writer structure"]
+impl crate::Writable for CACHE_MMU_OWNER_SPEC {
+    type Safety = crate::Unsafe;
+    const ZERO_TO_MODIFY_FIELDS_BITMAP: u32 = 0;
+    const ONE_TO_MODIFY_FIELDS_BITMAP: u32 = 0;
+}
+#[doc = "`reset()` method sets CACHE_MMU_OWNER to value 0"]
+impl crate::Resettable for CACHE_MMU_OWNER_SPEC {
+    const RESET_VALUE: u32 = 0;
+}