Create a comparative analysis of 5 browser extensions for productivity: 1) ZebuClip - clipboard manager with batch processing 2) OpenCookie - privacy-focused cookie editor 3) Lumno - universal browser search 4) E2N - web-to-notebook tool 5) SubMask - language learning assistant. For each, summarize: core functionality, technical approach, privacy considerations, and ideal use cases. Present as a markdown table with pros/cons and recommendations for different user types (developers, researchers, students).