refactor: drop the mojibake workaround from slugifyStem

slugifyStem carried `.replaceAll('ΓÇÖ', "'")`, which patched a corrupted
apostrophe at the slug layer so three notes with mojibake filenames still
produced correct URLs. The underlying filenames are now repaired, so no stem
contains that sequence and the line is dead code that encodes an assumption
which is no longer true.

Proved it is dead rather than assuming: rebuilt and diffed all 411 generated
slugs against the previous build - identical, nothing moved.

The unit test asserted against the corrupted string, so it was testing the
workaround rather than the behaviour. It now uses the real repaired stem,
'A Farfetch’D Story', which exercises the same thing that actually matters -
that U+2019 becomes a hyphen - and still expects 'a-farfetch-d-story'. Added a
case for 'Fused Dimensions' to pin the non-breaking-space folding, since that
name previously carried U+00A0.

Also syncs the catalog for the Fused Dimensions rename. Verified: npm run check
(0 errors, vitest 9/9), npm run build (486 pages), CI=1 npm run test:ui (8/8),
deployed; live 200 on all seven repaired URLs and the h1 renders without NBSP.

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

data/catalog.json

@@ -7864,8 +7864,8 @@
       ]
     },
     {
-      "stem": "Fused Dimensions",
-      "title": "Pokémon Fused Dimensions",
+      "stem": "Fused Dimensions",
+      "title": "Pokémon Fused Dimensions",
       "platform": "GBA",
       "base": "FireRed",
       "version": null,