copy(web): replace em dashes in public copy

Rewrites every visitor-facing string that used an em dash, choosing the
punctuation for what the dash was doing: a colon before a list or
explanation, a comma for an aside, a full stop between two thoughts,
parentheses for an aside mid-sentence. Covers page titles and meta
descriptions, the home and admissions guide copy, school page headings
and notes, the compare page, metric labels and tooltips.

Two rewrites also fix the sentence around them: the closure banner no
longer repeats "proposed for closure", and the cut-off caveat's list of
priorities now parses.

A lone dash marking a missing value in a table cell stays: it is a data
convention, not prose. A Jest guard walks the source with the TypeScript
parser and fails on any other em dash in a string or JSX text node.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

nextjs-app/components/school/lastDistanceOffered.ts

@@ -32,7 +32,7 @@ export interface CutoffDisplay {
 /** What the cut-off measures, and what it does not. Identical on both templates. */
 export const CUTOFF_NOTE =
   'The furthest home offered a place, after higher priorities such as siblings, ' +
-  'faith and EHCP were applied. It is not a fixed catchment — it moves every year ' +
+  'faith and EHCP were applied. It is not a fixed catchment. It moves every year ' +
   'with the number of applications.';
 
 /** Straight-line, because that is how councils measure it. */
@@ -54,7 +54,7 @@ export function describeCutoff(
     entryYear: formatEntryYear(distance.year),
     routeNote:
       routes > 1
-        ? `Furthest of ${routes} admission routes at this school — the one that ` +
+        ? `Furthest of ${routes} admission routes at this school. The one that ` +
           'applies to your child may have had a shorter cut-off.'
         : null,
   };
@@ -122,10 +122,10 @@ export function compareToCutoff(
   const cutoffPhrase = `the September ${year} cut-off of ${cutoffLabel}`;
   const headline =
     verdict === 'inside'
-      ? `${label} away — inside ${cutoffPhrase}.`
+      ? `${label} away, inside ${cutoffPhrase}.`
       : verdict === 'outside'
-        ? `${label} away — beyond ${cutoffPhrase}.`
-        : `${label} away — too close to ${cutoffPhrase} to call.`;
+        ? `${label} away, beyond ${cutoffPhrase}.`
+        : `${label} away, too close to ${cutoffPhrase} to call.`;
 
   const detail =
     verdict === 'too-close'
@@ -156,11 +156,11 @@ export function compareToCutoff(
  */
 export const CUTOFF_CHECK_CAVEAT =
   'Distance is the last criterion applied. Places go first to children in care, '
-  + 'EHCP places, siblings and — at faith schools — on faith criteria, so a home '
+  + 'EHCP places and siblings, and at faith schools by faith criteria, so a home '
   + 'inside the distance can still miss out. Figures are straight-line distances '
   + 'and not a catchment boundary; some authorities measure a walking route '
   + "instead, which is always longer for the same home. Next year's cut-off "
-  + "depends on next year's applicants — always check the school's own "
+  + "depends on next year's applicants, so always check the school's own "
   + 'admissions policy.';
 
 // ---------------------------------------------------------------------------