Surface unread counts on sidebar launcher rows

The design's Slack/Linear/Gmail rows show numeric badges (12, 3) that
real apps publish in their tab title prefix — "(12) Slack | …",
"(3) Inbox — Linear", "(99+) Gmail". Add a pure parser
ely_domain::parse_title_unread_count that recognises the leading
"(N)" pattern and surfaces it through BrowserTab::unread_count(); the
sidebar launcher row renders a glass pill badge whenever the count
is non-zero, capped at "99+" for very high counts.

No domain field, no fabrication: the badge appears only when a real
website publishes its own unread count via the title. Tests cover
canonical formats, non-prefixed titles, leading whitespace, and
non-numeric / overflow inputs.

crates/ely_domain/src/tab.rs

@@ -106,6 +106,11 @@ impl BrowserTab {
         &self.title
     }
 
+    #[must_use]
+    pub fn unread_count(&self) -> u32 {
+        parse_title_unread_count(&self.title)
+    }
+
     #[must_use]
     pub fn url(&self) -> &UrlText {
         &self.url
@@ -274,3 +279,46 @@ pub fn validate_zoom_percent(value: u16) -> Result<u16, DomainError> {
 
     Err(DomainError::InvalidZoomPercent { value, min: MIN_ZOOM_PERCENT, max: MAX_ZOOM_PERCENT })
 }
+
+#[must_use]
+pub fn parse_title_unread_count(title: &str) -> u32 {
+    let trimmed = title.trim_start();
+    let Some(rest) = trimmed.strip_prefix('(') else {
+        return 0;
+    };
+    let Some(close) = rest.find(')') else {
+        return 0;
+    };
+    rest[..close].parse::<u32>().unwrap_or(0)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::parse_title_unread_count;
+
+    #[test]
+    fn parses_leading_parenthesised_count() {
+        assert_eq!(parse_title_unread_count("(12) Slack"), 12);
+        assert_eq!(parse_title_unread_count("(3) Inbox — Linear"), 3);
+        assert_eq!(parse_title_unread_count("(0) Quiet"), 0);
+    }
+
+    #[test]
+    fn ignores_non_prefixed_titles() {
+        assert_eq!(parse_title_unread_count("Slack"), 0);
+        assert_eq!(parse_title_unread_count("Inbox (12)"), 0);
+        assert_eq!(parse_title_unread_count(""), 0);
+    }
+
+    #[test]
+    fn rejects_non_numeric_or_overflow_counts() {
+        assert_eq!(parse_title_unread_count("(99+) Gmail"), 0);
+        assert_eq!(parse_title_unread_count("(abc) Mail"), 0);
+        assert_eq!(parse_title_unread_count("(99999999999999999999) huge"), 0);
+    }
+
+    #[test]
+    fn tolerates_leading_whitespace() {
+        assert_eq!(parse_title_unread_count("   (7) Slack"), 7);
+    }
+}