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/unicode-ident/tests/static_size.rs

@@ -0,0 +1,95 @@
+#![allow(clippy::let_underscore_untyped, clippy::unreadable_literal)]
+
+use std::mem::size_of_val;
+
+#[test]
+fn test_size() {
+    #[allow(dead_code)]
+    #[path = "../src/tables.rs"]
+    mod tables;
+
+    let size = size_of_val(&tables::ASCII_START)
+        + size_of_val(&tables::ASCII_CONTINUE)
+        + size_of_val(&tables::TRIE_START)
+        + size_of_val(&tables::TRIE_CONTINUE)
+        + size_of_val(&tables::LEAF);
+    assert_eq!(10056, size);
+}
+
+#[test]
+fn test_xid_size() {
+    #[deny(dead_code)]
+    #[path = "tables/mod.rs"]
+    mod tables;
+
+    let size = size_of_val(tables::XID_START) + size_of_val(tables::XID_CONTINUE);
+    assert_eq!(11976, size);
+
+    let _ = tables::BY_NAME;
+}
+
+#[cfg(target_pointer_width = "64")]
+#[test]
+fn test_trieset_size() {
+    #[deny(dead_code)]
+    #[allow(clippy::redundant_static_lifetimes)]
+    #[path = "trie/trie.rs"]
+    mod trie;
+
+    let ucd_trie::TrieSet {
+        tree1_level1,
+        tree2_level1,
+        tree2_level2,
+        tree3_level1,
+        tree3_level2,
+        tree3_level3,
+    } = *trie::XID_START;
+
+    let start_size = size_of_val(trie::XID_START)
+        + size_of_val(tree1_level1)
+        + size_of_val(tree2_level1)
+        + size_of_val(tree2_level2)
+        + size_of_val(tree3_level1)
+        + size_of_val(tree3_level2)
+        + size_of_val(tree3_level3);
+
+    let ucd_trie::TrieSet {
+        tree1_level1,
+        tree2_level1,
+        tree2_level2,
+        tree3_level1,
+        tree3_level2,
+        tree3_level3,
+    } = *trie::XID_CONTINUE;
+
+    let continue_size = size_of_val(trie::XID_CONTINUE)
+        + size_of_val(tree1_level1)
+        + size_of_val(tree2_level1)
+        + size_of_val(tree2_level2)
+        + size_of_val(tree3_level1)
+        + size_of_val(tree3_level2)
+        + size_of_val(tree3_level3);
+
+    assert_eq!(10392, start_size + continue_size);
+
+    let _ = trie::BY_NAME;
+}
+
+#[test]
+fn test_fst_size() {
+    let xid_start_fst = include_bytes!("fst/xid_start.fst");
+    let xid_continue_fst = include_bytes!("fst/xid_continue.fst");
+    let size = xid_start_fst.len() + xid_continue_fst.len();
+    assert_eq!(143513, size);
+}
+
+#[test]
+fn test_roaring_size() {
+    #[path = "roaring/mod.rs"]
+    mod roaring;
+
+    let xid_start_bitmap = roaring::xid_start_bitmap();
+    let xid_continue_bitmap = roaring::xid_continue_bitmap();
+    let size = xid_start_bitmap.serialized_size() + xid_continue_bitmap.serialized_size();
+    assert_eq!(66104, size);
+}