Reject non-hex characters in live::parse_color

Found while testing crates/engine/src/live.rs:85

Co-Authored-By: Claude Haiku 5.5 <[email protected]>
Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

crates/engine/src/live.rs

@@ -81,7 +81,7 @@ pub const PEOPLE: [&str; 8] = ["#0D99FF", "#9747FF", "#14AE5C", "#F24822", "#D97
 
 /// `#RRGGBB` → (r, g, b); `None` for anything else.
 pub fn parse_color(s: &str) -> Option<(u8, u8, u8)> {
-    let hex = s.strip_prefix('#').filter(|h| h.len() == 6 && h.is_ascii())?;
+    let hex = s.strip_prefix('#').filter(|h| h.len() == 6 && h.bytes().all(|b| b.is_ascii_hexdigit()))?;
     let byte = |i: usize| hex.get(i..i + 2).and_then(|b| u8::from_str_radix(b, 16).ok());
     Some((byte(0)?, byte(2)?, byte(4)?))
 }

crates/engine/tests/live_parse_color.rs

@@ -0,0 +1,8 @@
+use figcraft_engine::live::parse_color;
+
+#[test]
+fn parse_color_rejects_signs_and_non_hex() {
+    assert_eq!(parse_color("#+1+2+3"), None);
+    assert_eq!(parse_color("#-1-2-3"), None);
+    assert_eq!(parse_color("#0D99FF"), Some((13, 153, 255)));
+}