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/object/tests/round_trip/common.rs

@@ -0,0 +1,241 @@
+#![cfg(all(feature = "read", feature = "write"))]
+
+use object::read::{Object, ObjectSection, ObjectSymbol};
+use object::{read, write};
+use object::{
+    Architecture, BinaryFormat, Endianness, SectionKind, SymbolFlags, SymbolKind, SymbolScope,
+};
+
+#[test]
+fn coff_x86_64_common() {
+    let mut object =
+        write::Object::new(BinaryFormat::Coff, Architecture::X86_64, Endianness::Little);
+
+    let symbol = write::Symbol {
+        name: b"v1".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 4, 4);
+
+    let symbol = write::Symbol {
+        name: b"v2".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 8, 8);
+
+    // Also check undefined symbols, which are very similar.
+    let symbol = write::Symbol {
+        name: b"v3".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_symbol(symbol);
+
+    let bytes = object.write().unwrap();
+
+    //std::fs::write(&"common.o", &bytes).unwrap();
+
+    let object = read::File::parse(&*bytes).unwrap();
+    assert_eq!(object.format(), BinaryFormat::Coff);
+    assert_eq!(object.architecture(), Architecture::X86_64);
+
+    let mut symbols = object.symbols();
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("v1"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Common);
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 4);
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("v2"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Common);
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 8);
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("v3"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Undefined);
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 0);
+
+    let symbol = symbols.next();
+    assert!(symbol.is_none(), "unexpected symbol {:?}", symbol);
+}
+
+#[test]
+fn elf_x86_64_common() {
+    let mut object =
+        write::Object::new(BinaryFormat::Elf, Architecture::X86_64, Endianness::Little);
+
+    let symbol = write::Symbol {
+        name: b"v1".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 4, 4);
+
+    let symbol = write::Symbol {
+        name: b"v2".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 8, 8);
+
+    let bytes = object.write().unwrap();
+
+    //std::fs::write(&"common.o", &bytes).unwrap();
+
+    let object = read::File::parse(&*bytes).unwrap();
+    assert_eq!(object.format(), BinaryFormat::Elf);
+    assert_eq!(object.architecture(), Architecture::X86_64);
+
+    let mut symbols = object.symbols();
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("v1"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Common);
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 4);
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("v2"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Common);
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 8);
+
+    let symbol = symbols.next();
+    assert!(symbol.is_none(), "unexpected symbol {:?}", symbol);
+}
+
+#[test]
+fn macho_x86_64_common() {
+    let mut object = write::Object::new(
+        BinaryFormat::MachO,
+        Architecture::X86_64,
+        Endianness::Little,
+    );
+
+    let symbol = write::Symbol {
+        name: b"v1".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 4, 4);
+
+    let symbol = write::Symbol {
+        name: b"v2".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_common_symbol(symbol, 8, 8);
+
+    let bytes = object.write().unwrap();
+
+    //std::fs::write(&"common.o", &bytes).unwrap();
+
+    let object = read::File::parse(&*bytes).unwrap();
+    assert_eq!(object.format(), BinaryFormat::MachO);
+    assert_eq!(object.architecture(), Architecture::X86_64);
+
+    let mut sections = object.sections();
+
+    let common = sections.next().unwrap();
+    println!("{:?}", common);
+    let common_index = common.index();
+    assert_eq!(common.name(), Ok("__common"));
+    assert_eq!(common.segment_name(), Ok(Some("__DATA")));
+    assert_eq!(common.kind(), SectionKind::Common);
+    assert_eq!(common.size(), 16);
+    assert_eq!(common.data(), Ok(&[][..]));
+
+    let section = sections.next();
+    assert!(section.is_none(), "unexpected section {:?}", section);
+
+    let mut symbols = object.symbols();
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("_v1"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section_index(), Some(common_index));
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 0);
+
+    let symbol = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Ok("_v2"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section_index(), Some(common_index));
+    assert_eq!(symbol.scope(), SymbolScope::Linkage);
+    assert!(!symbol.is_weak());
+    assert!(!symbol.is_undefined());
+    assert_eq!(symbol.address(), 8);
+
+    let symbol = symbols.next();
+    assert!(symbol.is_none(), "unexpected symbol {:?}", symbol);
+}