fix: order nearby schools by distance, not by how alike they are

Reported from staging: a Catholic primary showed six Catholic primaries, none
of them close enough to be a real option, and omitted the community school
down the road.

Three causes, compounding. Ranking put tier before distance, so a faith match
at 2.9 miles outranked a community school at 0.3. The ENOUGH=3 stopping rule —
added so a cap of six would not drag in weak distant matches — filled the row
from the best tier before it ever widened, which is what made every card
Catholic. And a 3-mile tier-1 radius is sane for a secondary and most of a city
for a primary, whose catchments are routinely under a mile.

The premise was backwards. For a parent, distance is a constraint and intake is
a preference; a school beyond a primary catchment is not a weaker option, it is
not an option. So distance now decides the order and nothing else does. The
hard filters are untouched — they were always where the defensibility lived.
Similarity survives as chips on the card: reported, so a reader applies their
own weighting, rather than ranked, so we apply ours for them.

Reach is capped per phase (primary 2, secondary 6, post-16 10) as a sanity
bound, not a target: ordering already handles density, so the cap only decides
what happens where an area is sparse. A primary with nothing inside two miles
now renders no section, which is the honest answer.

Deleted: the tier system, the stopping rule, the tier-dependent lede, the
`tier` field, the tier-3 fallback chip and its style. select_similar also stops
taking is_secondary — it reads the phase from the subject's own row, so no
caller can hand it one that disagrees with the data.

The heading is now "Other schools nearby". The hard filters still guarantee a
comparable set, but nothing ranks on likeness, so the heading no longer says it
does.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

e2e/tests/journeys.spec.ts

@@ -2736,7 +2736,7 @@ test('the content sitemap lists the about page and is advertised in robots', asy
 });
 
 /**
- * Similar schools nearby.
+ * Other schools nearby.
  *
  * The section is absent by design where fewer than two schools qualify, and the
  * arrows are absent where three cards fit, so this asserts each part of the
@@ -2746,12 +2746,12 @@ test('the content sitemap lists the about page and is advertised in robots', asy
  * which jsdom cannot measure because it has no layout, and the scroll position
  * surviving a selection, which is DOM state rather than React state.
  */
-test('similar schools link on to other schools and into compare', async ({ page }) => {
+test('nearby schools link on to other schools and into compare', async ({ page }) => {
   await searchByName(page, 'Primary');
   await schoolLinks(page).first().click();
   await page.waitForURL(/\/school\//);
 
-  const section = page.locator('#similar');
+  const section = page.locator('#nearby');
   if ((await section.count()) === 0) {
     test.skip(true, 'No qualifying similar schools for this school');
   }
@@ -2793,7 +2793,7 @@ test('similar schools link on to other schools and into compare', async ({ page
 });
 
 /**
- * The section at MOBILE.md's three reference widths.
+ * The nearby-schools section at MOBILE.md's three reference widths.
  *
  * MOBILE.md asks for exactly this check and records that it was not written
  * because "Playwright isn't currently in the project dependency set". That is
@@ -2801,13 +2801,13 @@ test('similar schools link on to other schools and into compare', async ({ page
  * to the page this feature touches.
  */
 for (const width of [360, 390, 430]) {
-  test(`similar schools survives a ${width}px viewport`, async ({ page }) => {
+  test(`nearby schools survives a ${width}px viewport`, async ({ page }) => {
     await page.setViewportSize({ width, height: 800 });
     await searchByName(page, 'Primary');
     await schoolLinks(page).first().click();
     await page.waitForURL(/\/school\//);
 
-    const section = page.locator('#similar');
+    const section = page.locator('#nearby');
     if ((await section.count()) === 0) {
       test.skip(true, 'No qualifying similar schools for this school');
     }