Removed all code and logic related to WeChat V3 key extraction, including darwin and windows V3 extractors. Updated extractor selection to return an error for V3. Refactored Windows DLL extractor to run DLL and native (Dart-style) memory scan in parallel for V4, reporting keys as soon as found. Improved image key acquisition flow in the TUI and updated documentation to reflect the new focus on V4, parallel key extraction, and the deprecation of V3 support.
