refactor: move std-dev info to accordion, remove tooltip (#19)

- Add "Round spread" row (±stdDev, range lo–hi) to desktop accordion
  (player-history.ejs) and mobile card expanded section (ratings-cards.ejs)
- Remove .std-dev-tooltip div and .std-dev-inline span from table partial
- Remove stdDevTooltipText, updateStdDevInline, initRatingsTooltips helpers
  and all call sites from players.js
- Remove .std-dev-tooltip and .std-dev-inline CSS rules; drop cursor:help
  from .rating-value

public/css/players.css

@@ -14,7 +14,6 @@
 
 .rating-value {
     font-variant-numeric: tabular-nums;
-    cursor: help;
 }
 
 .pdga-number {
@@ -47,12 +46,6 @@
     font-variant-numeric: tabular-nums;
 }
 
-.std-dev-inline {
-    color: var(--text-muted);
-    font-size: 12px;
-    font-variant-numeric: tabular-nums;
-}
-
 .difference {
     font-weight: 600;
 }
@@ -101,24 +94,6 @@
     box-shadow: var(--shadow-lg);
 }
 
-/* ── Tooltips ─────────────────────────────────── */
-
-.std-dev-tooltip {
-    position: fixed;
-    background: var(--navy-900);
-    color: var(--text-inverse);
-    padding: 6px 10px;
-    border-radius: var(--radius-sm);
-    font-size: 12px;
-    font-family: var(--font-mono);
-    pointer-events: none;
-    z-index: 10000;
-    display: none;
-    white-space: pre;
-    box-shadow: var(--shadow-lg);
-    font-weight: 400;
-}
-
 /* ── Debug Icon ───────────────────────────────── */
 
 .debug-icon:hover {