profiler scan: check/uncheck-all toggle for the ignore-contents list

Adds an 'All' header checkbox next to 'Ignore contents of files:' that
checks or unchecks every file; it reflects the list state (checked only
when all are checked, indeterminate on a mixed selection) and updates on
individual checkbox changes. RU label: 'Все'. Docs synced, tests for the
toggle/state helpers. SW cache v77 -> v78.

frontend/sw.js

@@ -1,4 +1,4 @@
-const CACHE = 'otaman-v77';
+const CACHE = 'otaman-v78';
 const URLS = [
   'index.html',
   'help.html',