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/chrono/src/offset/local/win_bindings.rs

@@ -0,0 +1,59 @@
+#![allow(non_snake_case, non_upper_case_globals, non_camel_case_types, dead_code, clippy::all)]
+
+windows_link::link!("kernel32.dll" "system" fn GetTimeZoneInformationForYear(wyear : u16, pdtzi : *const DYNAMIC_TIME_ZONE_INFORMATION, ptzi : *mut TIME_ZONE_INFORMATION) -> BOOL);
+windows_link::link!("kernel32.dll" "system" fn SystemTimeToFileTime(lpsystemtime : *const SYSTEMTIME, lpfiletime : *mut FILETIME) -> BOOL);
+windows_link::link!("kernel32.dll" "system" fn SystemTimeToTzSpecificLocalTime(lptimezoneinformation : *const TIME_ZONE_INFORMATION, lpuniversaltime : *const SYSTEMTIME, lplocaltime : *mut SYSTEMTIME) -> BOOL);
+windows_link::link!("kernel32.dll" "system" fn TzSpecificLocalTimeToSystemTime(lptimezoneinformation : *const TIME_ZONE_INFORMATION, lplocaltime : *const SYSTEMTIME, lpuniversaltime : *mut SYSTEMTIME) -> BOOL);
+pub type BOOL = i32;
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct DYNAMIC_TIME_ZONE_INFORMATION {
+    pub Bias: i32,
+    pub StandardName: [u16; 32],
+    pub StandardDate: SYSTEMTIME,
+    pub StandardBias: i32,
+    pub DaylightName: [u16; 32],
+    pub DaylightDate: SYSTEMTIME,
+    pub DaylightBias: i32,
+    pub TimeZoneKeyName: [u16; 128],
+    pub DynamicDaylightTimeDisabled: bool,
+}
+impl Default for DYNAMIC_TIME_ZONE_INFORMATION {
+    fn default() -> Self {
+        unsafe { core::mem::zeroed() }
+    }
+}
+#[repr(C)]
+#[derive(Clone, Copy, Default)]
+pub struct FILETIME {
+    pub dwLowDateTime: u32,
+    pub dwHighDateTime: u32,
+}
+#[repr(C)]
+#[derive(Clone, Copy, Default)]
+pub struct SYSTEMTIME {
+    pub wYear: u16,
+    pub wMonth: u16,
+    pub wDayOfWeek: u16,
+    pub wDay: u16,
+    pub wHour: u16,
+    pub wMinute: u16,
+    pub wSecond: u16,
+    pub wMilliseconds: u16,
+}
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub struct TIME_ZONE_INFORMATION {
+    pub Bias: i32,
+    pub StandardName: [u16; 32],
+    pub StandardDate: SYSTEMTIME,
+    pub StandardBias: i32,
+    pub DaylightName: [u16; 32],
+    pub DaylightDate: SYSTEMTIME,
+    pub DaylightBias: i32,
+}
+impl Default for TIME_ZONE_INFORMATION {
+    fn default() -> Self {
+        unsafe { core::mem::zeroed() }
+    }
+}