Minor UI improvements

[hjamet]

🚀 Major Features & UX Overhaul: Keyboard Shortcuts, File Handling, and Polished UI

Description

This pull request introduces significant new features to boost productivity and implements a comprehensive set of UI/UX enhancements to create a more stable, intuitive, and polished chat experience. It adds global keyboard shortcuts and direct file handling while refining the core application layout, message interactions, and input field behavior.

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⌨️ Global Keyboard Shortcuts

• Reusable Hook: A new useKeyboardShortcuts hook has been created to capture and dispatch global shortcuts. It is configured to ignore key presses when the focus is inside inputs, textareas, or content-editable elements to prevent conflicts with typing.
• App-Wide Integration: Shortcuts are registered in the global ThemeProvider, enabling page navigation (e.g., Alt+H for Home) and actions like focusing the conversation search field (Alt+F).
• Enhanced Discoverability: Shortcut labels are now displayed in the sidebar next to their corresponding navigation items using a styled <kbd> element, making them easy for users to discover and learn.

✨ Enhanced Chat Input

• Paste & Drag-and-Drop Files: Users can now paste or drag-and-drop files and images directly into the chat input area. This is seamlessly integrated with the existing uploadFiles handler to centralize file processing and ensure UI state is updated consistently.
• Visual Feedback: A dashed outline now appears around the input area when a user is dragging a file over it, providing clear visual feedback.

- **Improved Slash Command Navigation**: The slash command menu is now fully navigable with the keyboard. `ArrowUp` and `ArrowDown` key presses are correctly forwarded to the command list, while the `Enter` key properly selects a command without submitting the chat. - **Consistent Positioning**: The chat input is now reliably positioned at the bottom of the viewport. It remains sticky during scrolling and maintains consistent spacing, resolving various visual glitches.

🎨 UI & UX Polish

• Single-Scroll Layout: The application now enforces a single, internal scroll container for the chat history by setting body { overflow: hidden; }. This eliminates the "double scrollbar" issue and provides a cleaner, more native app-like feel.
• Stable Text Selection: Text selection within messages is now persistent. The highlight remains visible even when the mouse leaves the message bubble, making it reliable and easy to copy content.
• Responsive Message Bubbles: Message bubbles now correctly size to fit their content. Short messages no longer stretch to fill the available width, creating a more natural and readable conversation flow. (Also smoother animation)
• Unified Message Footer: The message footer (timestamp, actions) now appears consistently on hover for all messages.
• Improved Click Affordance: The cursor now changes to a pointer when hovering over the account menu trigger and its dropdown items, providing a clearer visual cue for clickable elements.
• Small hover animations on Agents proposals on the Home Page