Fix Android pause icon and clarify public user stats

[pitill0]

Summary

This PR fixes the Android player pause icon and clarifies the public user count.

Changes

• Replaces the Unicode pause glyph with a CSS-rendered pause icon.
  • Avoids inconsistent glyph rendering on Android browsers.
  • Keeps the existing player control structure and responsive behavior.
• Changes the public stats label from users to active users.
  • Reflects the actual backend criteria.
  • Public stats only count active, approved users with a valid password.
  • The Admin panel still lists every known account, including pending, disabled or legacy accounts.
• Updates the public stats UI regression test to cover the new label.

Root cause

Android pause icon

The pause state used the Unicode glyph ❚❚. Its appearance depends on the font selected by the browser and was rendered incorrectly on Android as two stop-like symbols.

The icon is now drawn with CSS pseudo-elements, making it independent of platform fonts.

Public user count

The public counter was labelled simply as users, although its query intentionally excludes inactive, pending, rejected and passwordless accounts. The new label makes that distinction explicit without changing the underlying statistics.

Validation

• Player play, pause, resume and stop controls work on desktop.
• Pause icon renders correctly on Android.
• Player controls remain aligned on mobile and desktop.
• Public stats display active user for a count of one.
• Public stats display active users for plural counts.
• Relevant tests pass.
• Full CI passes.

Closes #199