refactor(handlers): Phase 3 - create SearchHandler for query operations

- Create SearchHandler struct with db field
- Add NewSearchHandler constructor
- Note: SearchMediaItems already moved to MediaHandler in Phase 2
- SearchHandler reserved for future search-specific operations

This is Phase 3 of the ebook.go refactoring plan.

internal/handlers/search.go

@@ -0,0 +1,20 @@
+package handlers
+
+import (
+	"bookhoard/internal/database"
+)
+
+// SearchHandler handles search, query, and filtered operations
+type SearchHandler struct {
+	db *database.Queries
+}
+
+// NewSearchHandler creates a new search handler
+func NewSearchHandler(db *database.Queries) *SearchHandler {
+	return &SearchHandler{
+		db: db,
+	}
+}
+
+// Note: SearchMediaItems was moved to MediaHandler in Phase 2
+// The SearchHandler is reserved for future search-specific operations