feat(ux): implement comprehensive UX audit fixes across all pages

Addresses 28 issues identified in UX audit (P0–P3 severity):

P0 — Critical:
- Fix compare URL sharing: seed ComparisonContext from SSR initialData
  when localStorage is empty, making /compare?urns=... links shareable
- Remove permanently broken "Avg. Scaled Score" column from school
  detail historical data table

P1 — High priority:
- Add radius selector (0.5–10 mi) to postcode search in FilterBar
- Make Add to Compare a toggle (remove) on SchoolCards
- Hide hero title/description once a search is active
- Show school count + quick-search prompts on empty landing page
- Compare empty state opens in-page school search modal directly
- Remove URN from school detail header (irrelevant to end users)
- Move map above performance chart in school detail page
- Add ← Back navigation to school detail page
- Add sort controls to search results (RWM%, distance, A–Z)
- Show metric descriptions below metric selector
- Expand ComparisonToast to list school names with per-school remove
- Add progress score explainer (0 = national average) throughout

P2 — Medium:
- Remove console.log statements from ComparisonView
- Colour-code comparison school cards to match chart line colours
- Replace plain loading text with LoadingSkeleton in ComparisonView
- Rankings empty state uses shared EmptyState component
- Rankings year filter shows actual year e.g. "2023 (Latest)"
- Rankings subtitle shows top-N count
- Add View link alongside Add button in rankings table
- Remove placeholder Privacy Policy / Terms links from footer
- Replace untappable 10px info icons with visible metric hint text
- Show active filter chips in search results header

P3 — Polish:
- Remove redundant "Home" nav link (logo already links home)
- Add / and Ctrl+K keyboard shortcut to focus search input
- Add Share button to compare page (copies URL to clipboard)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nextjs-app/components/ComparisonToast.tsx

@@ -7,7 +7,7 @@ import { usePathname } from 'next/navigation';
 import styles from './ComparisonToast.module.css';
 
 export function ComparisonToast() {
-  const { selectedSchools, clearAll } = useComparison();
+  const { selectedSchools, clearAll, removeSchool } = useComparison();
   const [mounted, setMounted] = useState(false);
   const pathname = usePathname();
 
@@ -25,19 +25,29 @@ export function ComparisonToast() {
   return (
     <div className={styles.toastContainer}>
       <div className={styles.toastContent}>
-        <div className={styles.toastInfo}>
-          <span className={styles.toastBadge}>{selectedSchools.length}</span>
-          <span className={styles.toastText}>
+        <div className={styles.toastHeader}>
+          <span className={styles.toastTitle}>
+            <span className={styles.toastBadge}>{selectedSchools.length}</span>
             {selectedSchools.length === 1 ? 'school' : 'schools'} selected
           </span>
         </div>
+        <div className={styles.schoolList}>
+          {selectedSchools.map(school => (
+            <div key={school.urn} className={styles.schoolItem}>
+              <span className={styles.schoolName} title={school.school_name}>
+                {school.school_name.length > 28 ? school.school_name.slice(0, 28) + '…' : school.school_name}
+              </span>
+              <button
+                onClick={() => removeSchool(school.urn)}
+                className={styles.removeSchoolBtn}
+                aria-label={`Remove ${school.school_name}`}
+              >×</button>
+            </div>
+          ))}
+        </div>
         <div className={styles.toastActions}>
-          <button onClick={clearAll} className={styles.btnClear}>
-            Clear
-          </button>
-          <Link href="/compare" className={styles.btnCompare}>
-            Compare Now
-          </Link>
+          <button onClick={clearAll} className={styles.btnClear}>Clear all</button>
+          <Link href="/compare" className={styles.btnCompare}>Compare Now</Link>
         </div>
       </div>
     </div>