feat: filter and search by tag

internal/web/templates/noteList.tmpl

@@ -23,6 +23,7 @@
 
 {{ define "renderSearch" }}
 {{ if ne .SearchTerm "" }}<h2>Matching results for query '{{ .SearchTerm }}'</h2>{{ end }}
+{{ if ne .TagFilter "" }}<h2>Filtered by tag '{{ .TagFilter }}'</h2>{{ end }}
   <ul class="search-results">
     {{ range .Notes }}
     <li {{ if eq .ID $.LastActive }}class="active-note"{{ end }}>