feat: add server-side session filtering with input bytes and human score

Replace client-side session table filtering with server-side filtering
via a new /fragments/recent-sessions htmx endpoint. Add InputBytes column
to session tables, Human score > 0 checkbox filter, and Sort by Input
Bytes option to help identify sessions with actual shell interaction.

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

internal/web/web.go

@@ -47,6 +47,7 @@ func NewServer(store storage.Store, logger *slog.Logger, metricsHandler http.Han
 	s.mux.HandleFunc("GET /fragments/stats", s.handleFragmentStats)
 	s.mux.HandleFunc("GET /fragments/active-sessions", s.handleFragmentActiveSessions)
 	s.mux.HandleFunc("GET /fragments/dashboard-content", s.handleFragmentDashboardContent)
+	s.mux.HandleFunc("GET /fragments/recent-sessions", s.handleFragmentRecentSessions)
 
 	if metricsHandler != nil {
 		h := metricsHandler