settings: unify transcode param styling and controls

- Style QP <input type=number> like the <select>s (it rendered with the
  default white background -> stood out); add a disabled (greyed) style.
- QP vs bitrate are now mutually DISABLED instead of hidden: QP mode
  greys the bitrate field, VBR/CBR greys the QP field. Hiding never
  worked because .tr-row label{display:flex} overrode [hidden].
- Replace SOFT/MEDIUM/HARD preset buttons with a "Готовый профиль"
  dropdown, placed last (rightmost) in the params row.

VERSION -> 0.0.120.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/static/style.css

@@ -147,7 +147,7 @@ input[type="checkbox"]:checked {
 }
 input[type="checkbox"]:checked::before { transform: translateX(18px); background: var(--ok); }
 input[type="checkbox"]:focus-visible { outline: 2px solid var(--ok); outline-offset: 2px; }
-input[type="date"], select {
+input[type="date"], input[type="number"], select {
   background: var(--panel-2); color: var(--text); border: 1px solid var(--border);
   padding: 6px 8px; border-radius: 6px;
 }
@@ -340,6 +340,8 @@ input[type="date"], select {
 .tr-row[hidden] { display: none; }
 .tr-row label { display: flex; flex-direction: column; gap: 5px; font-size: 12px; color: var(--text-dim); }
 .tr-row select { display: block; }
+.tr-row input[type="number"] { display: block; width: 80px; }
+.tr-row select:disabled, .tr-row input:disabled { opacity: .4; cursor: not-allowed; }
 /* общие пресеты перекодирования (SOFT / MEDIUM / HARD) */
 .tr-presets { flex-basis: 100%; display: flex; align-items: center; gap: 8px; padding-left: 28px; }
 .tr-preset {