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/nrf9160-pac/src/uicr_s.rs

@@ -0,0 +1,57 @@
+#[doc = r"Register block"]
+#[repr(C)]
+pub struct RegisterBlock {
+    #[doc = "0x00 - Access port protection"]
+    pub approtect: APPROTECT,
+    _reserved1: [u8; 0x10],
+    #[doc = "0x14 - Oscillator control"]
+    pub xosc32m: XOSC32M,
+    _reserved2: [u8; 0x04],
+    #[doc = "0x1c - HFXO clock source selection"]
+    pub hfxosrc: HFXOSRC,
+    #[doc = "0x20 - HFXO startup counter"]
+    pub hfxocnt: HFXOCNT,
+    _reserved4: [u8; 0x08],
+    #[doc = "0x2c - Secure access port protection"]
+    pub secureapprotect: SECUREAPPROTECT,
+    #[doc = "0x30 - Erase protection"]
+    pub eraseprotect: ERASEPROTECT,
+    _reserved6: [u8; 0xd4],
+    #[doc = "0x108..0x400 - Description collection: One time programmable memory"]
+    pub otp: [OTP; 190],
+    #[doc = "0x400..0x1000 - Unspecified"]
+    pub keyslot: KEYSLOT,
+}
+#[doc = "APPROTECT (rw) register accessor: an alias for `Reg<APPROTECT_SPEC>`"]
+pub type APPROTECT = crate::Reg<approtect::APPROTECT_SPEC>;
+#[doc = "Access port protection"]
+pub mod approtect;
+#[doc = "XOSC32M (rw) register accessor: an alias for `Reg<XOSC32M_SPEC>`"]
+pub type XOSC32M = crate::Reg<xosc32m::XOSC32M_SPEC>;
+#[doc = "Oscillator control"]
+pub mod xosc32m;
+#[doc = "HFXOSRC (rw) register accessor: an alias for `Reg<HFXOSRC_SPEC>`"]
+pub type HFXOSRC = crate::Reg<hfxosrc::HFXOSRC_SPEC>;
+#[doc = "HFXO clock source selection"]
+pub mod hfxosrc;
+#[doc = "HFXOCNT (rw) register accessor: an alias for `Reg<HFXOCNT_SPEC>`"]
+pub type HFXOCNT = crate::Reg<hfxocnt::HFXOCNT_SPEC>;
+#[doc = "HFXO startup counter"]
+pub mod hfxocnt;
+#[doc = "SECUREAPPROTECT (rw) register accessor: an alias for `Reg<SECUREAPPROTECT_SPEC>`"]
+pub type SECUREAPPROTECT = crate::Reg<secureapprotect::SECUREAPPROTECT_SPEC>;
+#[doc = "Secure access port protection"]
+pub mod secureapprotect;
+#[doc = "ERASEPROTECT (rw) register accessor: an alias for `Reg<ERASEPROTECT_SPEC>`"]
+pub type ERASEPROTECT = crate::Reg<eraseprotect::ERASEPROTECT_SPEC>;
+#[doc = "Erase protection"]
+pub mod eraseprotect;
+#[doc = "OTP (rw) register accessor: an alias for `Reg<OTP_SPEC>`"]
+pub type OTP = crate::Reg<otp::OTP_SPEC>;
+#[doc = "Description collection: One time programmable memory"]
+pub mod otp;
+#[doc = "Unspecified"]
+pub use keyslot::KEYSLOT;
+#[doc = r"Cluster"]
+#[doc = "Unspecified"]
+pub mod keyslot;