v0.4.0: Enhanced Tag Management UI & Centered Thumbnails

🚀 Features & Improvements

• Centered Square Thumbnails: Excel cells containing images are now generated as perfect squares based on the thumbnail size, and the image is precisely centered within the cell.
• Dual-Listbox UI for Tags: Completely revamped the GUI's tag selection interface. It now features a dual-listbox layout ("Available Tags" on the left, "Selected Tags" on the right) with Add -> and <- Remove buttons, making it much easier to manage large lists of tags.
• Double-Click Tag Assignment: You can now double-click tags in the GUI to quickly move them between the Available and Selected lists.
• Full Path Export Option: Added a new --fullpath CLI argument and a corresponding GUI checkbox. When enabled, the "Filename" column in the Excel output will contain the full absolute file path instead of just the file name.
• IPTC Date/Time Formatting: IPTC:DateCreated is now automatically formatted as YYYY/MM/DD, and IPTC:TimeCreated is formatted as HH:MM:SS for better readability in the generated Excel sheet.

🛠 Fixes & Refactoring

• GUI Window Resize: The default GUI window size has been widened to 800x400 to properly accommodate the new dual-listbox layout.
• Robust Image Scanning: Improved the manual "Scan Tags" feature in the GUI. Scanning an image to find custom tags now properly appends new tags to the list without resetting your existing selections.
• Row Height Limit: Added a safeguard to cap the maximum Excel row height at 409.5 points to comply with Excel's internal limits and prevent generation errors.