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/pulldown-cmark/tests/suite/smart_punct.rs

@@ -0,0 +1,201 @@
+// This file is auto-generated by the build script
+// Please, do not modify it manually
+
+use super::test_markdown_html;
+
+#[test]
+fn smart_punct_test_1() {
+    let original = r##""Hello," said the spider.
+"'Shelob' is my name."
+"##;
+    let expected = r##"<p>“Hello,” said the spider.
+“‘Shelob’ is my name.”</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_2() {
+    let original = r##"'A', 'B', and 'C' are letters.
+"##;
+    let expected = r##"<p>‘A’, ‘B’, and ‘C’ are letters.</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_3() {
+    let original = r##"'Oak,' 'elm,' and 'beech' are names of trees.
+So is 'pine.'
+"##;
+    let expected = r##"<p>‘Oak,’ ‘elm,’ and ‘beech’ are names of trees.
+So is ‘pine.’</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_4() {
+    let original = r##"'He said, "I want to go."'
+"##;
+    let expected = r##"<p>‘He said, “I want to go.”’</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_5() {
+    let original = r##"Were you alive in the 70's?
+"##;
+    let expected = r##"<p>Were you alive in the 70’s?</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_6() {
+    let original = r##"Here is some quoted '`code`' and a "[quoted link](url)".
+"##;
+    let expected = r##"<p>Here is some quoted ‘<code>code</code>’ and a “<a href="url">quoted link</a>”.</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_7() {
+    let original = r##"'tis the season to be 'jolly'
+"##;
+    let expected = r##"<p>’tis the season to be ‘jolly’</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_8() {
+    let original = r##"'We'll use Jane's boat and John's truck,' Jenna said.
+"##;
+    let expected = r##"<p>‘We’ll use Jane’s boat and John’s truck,’ Jenna said.</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_9() {
+    let original = r##""A paragraph with no closing quote.
+
+"Second paragraph by same speaker, in fiction."
+"##;
+    let expected = r##"<p>“A paragraph with no closing quote.</p>
+<p>“Second paragraph by same speaker, in fiction.”</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_10() {
+    let original = r##"[a]'s b'
+"##;
+    let expected = r##"<p>[a]’s b’</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_11() {
+    let original = r##"\"This is not smart.\"
+This isn\'t either.
+5\'8\"
+"##;
+    let expected = r##"<p>"This is not smart."
+This isn't either.
+5'8"</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_12() {
+    let original = r##"Some dashes:  em---em
+en--en
+em --- em
+en -- en
+2--3
+"##;
+    let expected = r##"<p>Some dashes:  em—em
+en–en
+em — em
+en – en
+2–3</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_13() {
+    let original = r##"one-
+two--
+three---
+four----
+five-----
+six------
+seven-------
+eight--------
+nine---------
+thirteen-------------.
+"##;
+    let expected = r##"<p>one-
+two–
+three—
+four––
+five—–
+six——
+seven—––
+eight––––
+nine———
+thirteen———––.</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_14() {
+    let original = r##"Escaped hyphens: \-- \-\-\-.
+"##;
+    let expected = r##"<p>Escaped hyphens: -- ---.</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_15() {
+    let original = r##"Ellipses...and...and....
+"##;
+    let expected = r##"<p>Ellipses…and…and….</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}
+
+#[test]
+fn smart_punct_test_16() {
+    let original = r##"No ellipses\.\.\.
+"##;
+    let expected = r##"<p>No ellipses...</p>
+"##;
+
+    test_markdown_html(original, expected, true, false, false);
+}