fix(bilirubin-ui): clarify neurotoxicity-risk-factor label + expandable AAP 2022 list

The dropdown was labeled just "Risk Factors" with option "None (lower risk)"
— ambiguous because AAP 2022 uses "risk factors" in two distinct senses:
(a) risk factors for developing hyperbilirubinemia (screening-only, do not
change thresholds) and (b) neurotoxicity risk factors (do change thresholds).
Only (b) belongs on the threshold nomogram, and a clinician glancing at the
form could easily pick wrong.

Changes:
- Label: "Neurotoxicity risk factors"
- Options: "Absent" / "Present (any one qualifies)" — removes the misleading
  "None (lower risk)" phrasing (no-risk curve actually has HIGHER thresholds)
- Expandable details listing the 6 specific AAP 2022 neurotoxicity risk
  factors (isoimmune hemolysis, G6PD, other hemolysis, sepsis, albumin <3.0,
  clinical instability <24h) with explicit note that GA <38w is handled by
  the per-week curve, not by this checkbox — prevents double-counting.

No data changes. Cite: Kemper et al., Pediatrics 2022;150(3):e2022058859, Box 2.

public/components/calculators.html

@@ -431,11 +431,23 @@
                     <input type="number" id="bili-tsb" min="0" max="35" step="0.1" placeholder="e.g. 12.5">
                   </div>
                   <div class="calc-field">
-                    <label>Risk Factors</label>
+                    <label>Neurotoxicity risk factors</label>
                     <select id="bili-risk">
-                      <option value="none">None (lower risk)</option>
-                      <option value="medium">Neurotoxicity risk factors present</option>
+                      <option value="none">Absent</option>
+                      <option value="medium">Present (any one qualifies)</option>
                     </select>
+                    <details style="font-size:11px;color:var(--g500);margin-top:4px;line-height:1.5;">
+                      <summary style="cursor:pointer;color:var(--g600);">What counts as a neurotoxicity risk factor?</summary>
+                      <ul style="margin:6px 0 0 16px;padding:0;">
+                        <li>Isoimmune hemolytic disease (positive DAT — ABO or Rh incompatibility)</li>
+                        <li>G6PD deficiency</li>
+                        <li>Other hemolytic disease (congenital or acquired)</li>
+                        <li>Sepsis</li>
+                        <li>Albumin &lt; 3.0 g/dL</li>
+                        <li>Significant clinical instability in the previous 24 hours</li>
+                      </ul>
+                      <div style="margin-top:6px;">Any one qualifies. Per AAP 2022 Box 2. Gestational age &lt; 38w is also a neurotoxicity risk per the guideline but is already accounted for by the per-week threshold curves — do NOT double-count it here.</div>
+                    </details>
                   </div>
                 </div>
                 <button id="btn-calc-bili-aap" class="btn-sm btn-primary" style="margin-top:12px;"><i class="fas fa-calculator"></i> Assess</button>