search: did-you-mean spelling suggestion + 9 tests

suggest/suggestN rank indexed terms by edit distance to a (misspelled) query
term, alphabetical tiebreak. 234/234.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/search/conformance.conf

@@ -32,6 +32,7 @@ PRELOADS=(
   lib/search/near.sx
   lib/search/syn.sx
   lib/search/rankq.sx
+  lib/search/suggest.sx
   lib/search/api.sx
   lib/search/testlib.sx
 )
@@ -50,4 +51,5 @@ SUITES=(
   "near:lib/search/tests/near.sx"
   "syn:lib/search/tests/syn.sx"
   "rankq:lib/search/tests/rankq.sx"
+  "suggest:lib/search/tests/suggest.sx"
 )