Fix stemmer stripping hyphens instead of splitting on them

The stemmer was concatenating tokens across hyphens (e.g. "BC3-IOS-1D8B"
→ "bc3ios1d8b") while the query sanitizer split on them, causing MySQL
MATCH AGAINST to never find the indexed token. Replace non-word chars
with spaces instead of stripping them so indexing and querying tokenize
consistently.

Requires search:reindex after deploy to rebuild existing search records.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/models/search/stemmer.rb

@@ -5,7 +5,7 @@ module Search::Stemmer
 
   def stem(value)
     if value.present?
-      value.gsub(/[^\w\s]/, "").split(/\s+/).map { |word| STEMMER.stem(word.downcase) }.join(" ")
+      value.gsub(/[^\w\s]/, " ").split(/\s+/).map { |word| STEMMER.stem(word.downcase) }.join(" ")
     else
       value
     end