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/lib.rs

@@ -64,7 +64,7 @@ pub use sync::{
 };
 pub use tab::{
     BrowserTab, DEFAULT_ZOOM_PERCENT, MAX_ZOOM_PERCENT, MIN_ZOOM_PERCENT, TabFlags, TabState,
-    ZOOM_PERCENT_STEP, validate_zoom_percent,
+    ZOOM_PERCENT_STEP, parse_title_unread_count, validate_zoom_percent,
 };
 pub use tab_group::TabGroup;
 pub use update::UpdatePolicy;