Improve mobile responsiveness and enhance user interface design

Finding memes is a pain. Have to scroll forever or guess the exact name.

**Current issues:**
- Can only search by exact name
- No way to browse by type
- Text editor is too basic
- No keyboard shortcuts

**What would help:**
- Category buttons (Funny, Reaction, etc.)
- Better search with clear button
- CAPS button for text
- Keyboard shortcuts like Ctrl+S

Would make creating memes so much faster and easier.

The issue names no files, tests, or entry points. Start by locating the frontend components for meme search, browsing, and text editing, then determine how keyboard input is handled. Done means the listed category browsing, clearer search, CAPS control, shortcuts, and responsive UI improvements are implemented and usable.

Written by the indexing model from the issue text.