Fix: Add dynamic word highlighting for fuzzy search

[anthony-tom1]

Context:

• Previously, when a user inputted words in the search bar, posts that had a sufficient edit distance appeared, but were not highlighting matching words.
• Post result words were not being highlighted when the search word and the post word did not share a contiguous substring of a sufficiently high length. For example, when a user inputs "helo", posts with "Hello" appear but are not highlighted because the words share "he" and "lo".
• This highlighting issue would have generated confusion for users, who likely would not have understood why specific post results were appearing from their search queries.

Fix Description:

• Highlights matched characters in search results when "Fuzzy match" is selected.
• For every input search, similar words in post results are highlighted.
• Uses Levenshtein minimal edit distance algorithm to determine word similarity
• For search queries with character insertions, the entire result word is highlighted.
• For search queries with character deletions or substitutions, shared characters are highlighted.

Files changed:

• public/src/modules/search.js: add getLevenshteinDistance, maxFuzzyEdits, getFuzzyMatchRanges, highlightFuzzyInText helpers; extend highlightMatches with a third matchWords parameter that switches between regex and per-word fuzzy highlighting
• public/src/client/search.js: read data-match-words from DOM and forward it to highlightMatches
• src/controllers/search.js: pass matchWords to template data
• vendor/nodebb-theme-harmony-main/templates/partials/search-results.tpl: add data-match-words attribute to the results container
• vendor/nodebb-theme-harmony-2.1.35/templates/partials/search-results.tpl: add data-match-words attribute to the results container

Screenshots:

Below are screenshots demonstrating the fuzzy search highlighting of different search queries ("Hello", "Helo", "word", "worlds", "jello").

Closes #27

[marcuswu5]

Looks like a good pr to me!