feat(a11y,admin): skip link, aria-labels, Ready label, title + age fixes

A11y:
- Skip-to-content link lands first in the body and jumps to #main
  past the header + sidebar for keyboard users.
- aria-label on the icon buttons that previously carried only an
  icon: hamburger menu (+ aria-controls="sidebar"), mobile search
  toggle, account menu (also drops the duplicate alt on the avatar
  since the button name already speaks the user's name).

Admin:
- Dashboard stat card renamed "Live Videos" → "Ready" (matches the
  DB status column; nothing on this card is actually live).

Settings:
- Duplicate "Prefer not to say" option on the Gender select — the
  empty placeholder shared the same label as the real option.
  Placeholder is now "Select…"; the real "Prefer not to say" option
  stays unchanged.
- Birthday picker caps the Year dropdown at (this year − 13) and
  the server-side register validation requires the same, so a
  client bypass can't let a <13 user through.

Titles:
- Admin layout uses "{Page} | TAKEONE" to match the frontend format
  (was "{Page} — TAKEONE"). User pages that said "| TAKEONE" literal
  now interpolate config('app.name'). Shorts and Welcome moved from
  " - " to " | " separator.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

resources/views/user/channel.blade.php

@@ -1205,7 +1205,13 @@ if ($oldLinks) {
                         <div class="ch-settings-field">
                             <label class="ch-settings-label">Gender</label>
                             <select name="gender" class="ch-settings-input" style="cursor:pointer;">
-                                <option value="">Prefer not to say</option>
+                                {{-- Empty value stands for "not chosen yet"
+                                     — different from the explicit "prefer not
+                                     to say" option. Previously both rendered
+                                     the same label, so users saw two
+                                     identical choices and the stats grouping
+                                     ambiguously bucketed one of them. --}}
+                                <option value="">Select…</option>
                                 <option value="male"              {{ old('gender', $user->gender) === 'male'              ? 'selected' : '' }}>Male</option>
                                 <option value="female"            {{ old('gender', $user->gender) === 'female'            ? 'selected' : '' }}>Female</option>
                                 <option value="prefer_not_to_say" {{ old('gender', $user->gender) === 'prefer_not_to_say' ? 'selected' : '' }}>Prefer not to say</option>