Unread counts, a window margin, blurred dialogs, softer group names

Each rise in an app's unread count while you are elsewhere adds to a
tally beside its name, and a dot on its icon in the rail. Looking at the
app is the only thing that clears it.

The window has no frame of its own, so the shell now keeps a 6px margin
in a normal window - the only part of it that is not a web page, and so
the only place left to grab. Full screen gives the room back.

Dialogs get the app blurred behind them. An app's webview paints above
the shell, so it has to be moved aside before a dialog can be seen at
all, and once moved there is nothing left to blur - a still taken on the
way out is the only way to keep the background there. It runs on a
blocking worker: its completion handler is on the main thread, and
waiting there deadlocks until the timeout and returns nothing.

Settings is much larger, the cog moved to the foot of the nav, group
names read as names rather than shouted headings, and "Refresh icons"
bumps a version every favicon URL carries, for the ones that cache wrong.

src-tauri/src/lib.rs

@@ -89,6 +89,7 @@ pub fn run() {
             commands::set_stage,
             commands::set_active,
             commands::hide_stage,
+            commands::stage_snapshot,
             commands::show_stage,
             commands::navigate_app,
             commands::history_go,
@@ -103,6 +104,8 @@ pub fn run() {
             commands::delete_group,
             commands::set_nav_collapsed,
             commands::set_theme,
+            commands::unread_counts,
+            commands::refresh_favicons,
             commands::focus_window,
             commands::notification_click,
             commands::set_zoom,