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/hashbrown/benches/set_ops.rs

@@ -0,0 +1,148 @@
+//! This file contains benchmarks for the ops traits implemented by HashSet.
+//! Each test is intended to have a defined larger and smaller set,
+//! but using a larger size for the "small" set works just as well.
+//!
+//! Each assigning test is done in the configuration that is faster. Cheating, I know.
+//! The exception to this is Sub, because there the result differs. So I made two benchmarks for Sub.
+
+#![feature(test)]
+
+extern crate test;
+
+use hashbrown::HashSet;
+use test::Bencher;
+
+/// The number of items to generate for the larger of the sets.
+const LARGE_SET_SIZE: usize = 1000;
+
+/// The number of items to generate for the smaller of the sets.
+const SMALL_SET_SIZE: usize = 100;
+
+/// The number of keys present in both sets.
+const OVERLAP: usize =
+    [LARGE_SET_SIZE, SMALL_SET_SIZE][(LARGE_SET_SIZE < SMALL_SET_SIZE) as usize] / 2;
+
+/// Creates a set containing end - start unique string elements.
+fn create_set(start: usize, end: usize) -> HashSet<String> {
+    (start..end).map(|nr| format!("key{}", nr)).collect()
+}
+
+#[bench]
+fn set_ops_bit_or(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| &large_set | &small_set)
+}
+
+#[bench]
+fn set_ops_bit_and(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| &large_set & &small_set)
+}
+
+#[bench]
+fn set_ops_bit_xor(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| &large_set ^ &small_set)
+}
+
+#[bench]
+fn set_ops_sub_large_small(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| &large_set - &small_set)
+}
+
+#[bench]
+fn set_ops_sub_small_large(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| &small_set - &large_set)
+}
+
+#[bench]
+fn set_ops_bit_or_assign(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| {
+        let mut set = large_set.clone();
+        set |= &small_set;
+        set
+    });
+}
+
+#[bench]
+fn set_ops_bit_and_assign(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| {
+        let mut set = small_set.clone();
+        set &= &large_set;
+        set
+    });
+}
+
+#[bench]
+fn set_ops_bit_xor_assign(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| {
+        let mut set = large_set.clone();
+        set ^= &small_set;
+        set
+    });
+}
+
+#[bench]
+fn set_ops_sub_assign_large_small(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| {
+        let mut set = large_set.clone();
+        set -= &small_set;
+        set
+    });
+}
+
+#[bench]
+fn set_ops_sub_assign_small_large(b: &mut Bencher) {
+    let large_set = create_set(0, LARGE_SET_SIZE);
+    let small_set = create_set(
+        LARGE_SET_SIZE - OVERLAP,
+        LARGE_SET_SIZE + SMALL_SET_SIZE - OVERLAP,
+    );
+    b.iter(|| {
+        let mut set = small_set.clone();
+        set -= &large_set;
+        set
+    });
+}