fix(docs): disable fuzzy matching in docs search (exact word or prefix only) (#65103)

The docs search theme (@easyops-cn/docusaurus-search-local) defaults
fuzzyMatchingDistance to 1, so every term also matched words one edit
away. Two user-visible failures on the 14.4 MB production index:

- Wrong results: 'keet' returned 'Microsoft Teams Meetings',
  'google_meet', 'Keep the Model Loaded' etc. — 'meet' and 'keep' are
  both one edit from 'keet', and the stemmer indexes 'meetings' as
  'meet'.
- Search appearing to die: fuzzy matching multiplies the generated
  lunr queries (distance matrix x maybe-typing variants x
  leave-one-out terms — up to 210 queries per keystroke on multi-word
  input), and fuzzy REQUIRED terms are the expensive scan kind. A
  typo'd 3-word query stalled the single-threaded search Web Worker
  for 25+ seconds; every later keystroke's search queued behind it,
  so the bar stopped returning results.

Setting fuzzyMatchingDistance: 0 keeps exact-word-or-prefix semantics
(keet -> keet*), which is the behavior users asked for. Validated by
running the plugin's shipped smartQueries/tokenize code against the
downloaded production search-index.json: legitimate queries (cron,
telegram, prefix 'memor') return identical results; worst-case typo
queries drop from 210 queries / 365-532ms per keystroke to 50-105 /
53-188ms; false 'keet' matches gone.

website/docusaurus.config.ts

@@ -62,6 +62,14 @@ const config: Config = {
           /^user-guide\/skills\/bundled\//,
           /^user-guide\/skills\/optional\//,
         ],
+        // Exact-or-prefix matching only (default is edit distance 1).
+        // With fuzzy distance 1, "keet" matched "meetings"/"keep" (one
+        // edit away after stemming), and multi-word typo queries against
+        // our ~14 MB index could stall the single-threaded search worker
+        // for 25s+, backing up every subsequent keystroke's search until
+        // the bar appeared dead. Distance 0 keeps "word or its extension"
+        // semantics (keet -> keet*) and removes the pathological scans.
+        fuzzyMatchingDistance: 0,
       }),
     ],
   ],