feat: add dependency check and refactor global state

- Implement check_deps function and --check-deps flag for environment validation.
- Add truecolor support detection for terminal swatches.
- Colorize --install output and stylized logo.
- Refactor script to use global constants for colors and paths.
- Improve installation logic with robust directory creation.
- Update README.md and --help with new flag and detailed prerequisites.

README.md

@@ -16,30 +16,56 @@ A feature-rich, portable CLI color utility for Linux, specializing in color pick
 
 ## 📋 Prerequisites
 
-To utilize all features, ensure the following are installed:
-- **KDE Plasma + Wayland:** Required for the `--pick` functionality.
-- **Python 3 + PyQt6:** Required for the picker helper.
-- **curl + jq:** Required for color naming support.
-- **wl-clipboard** (Wayland) or **xclip** (X11): Required for clipboard support.
-- **libnotify:** Required for desktop notifications (`notify-send`).
-- **ImageMagick (`magick` or `convert`):** Required for generating visual color swatches in desktop notifications.
+### Required Core Dependencies
+These are mandatory for the script to run and perform basic color conversions:
+- **Python 3:** Handles all color space math and conversions.
+- **jq:** Powers JSON formatting and internal data parsing.
+
+### Optional Feature Dependencies
+These enable specific functionality and can be installed as needed:
+- **KDE Plasma (Wayland):** Required for screen color picking (`--pick`).
+- **Python 3 PyQt6:** Required for the KDE color picker DBus interface.
+- **wl-clipboard** or **xclip:** Enables copying results to the system clipboard (`--copy`).
+- **curl:** Required for fetching human-readable color names from the web (`--name`).
+- **libnotify:** Enables desktop notifications (`--notify`).
+- **ImageMagick:** Generates visual color swatch icons for notifications (`--swatch`).
+- **Truecolor Terminal Emulator:** Required for accurate visual swatches in terminal output (`--swatch`).
+
+> **Tip:** Use `color-tool --check-deps` to quickly see which dependencies are currently met on your system.
 
 ## 🚀 Installation
 
+### Automatic Installation (Recommended)
+
 You can download the script directly from the [latest release](https://git.rootiest.dev/rootiest/color-tool/releases/latest) and install it:
 
 ```bash
-curl -sSLO https://git.rootiest.dev/rootiest/color-tool/releases/download/latest/color-tool
-chmod +x color-tool
-./color-tool --install
+# Download and install the latest version of the color-tool script
+curl -sSLO https://git.rootiest.dev/rootiest/color-tool/releases/download/latest/color-tool && bash color-tool --install && rm ./color-tool
 ```
 
 This will:
-1. Move the script to `~/.local/share/color-tool/`.
+1. Install the script to `~/.local/share/color-tool/`.
 2. Symlink the binary to `~/.local/bin/color-tool`.
 3. Generate a sample configuration at `~/.config/color-tool/config.toml`.
 4. Create a `.desktop` entry so you can launch the picker from your application menu.
 5. Verify and warn about any missing optional or required system dependencies.
+6. Clean up the downloaded script after installation.
+
+### Manual Usage
+
+Alternatively, you can [download the script](https://git.rootiest.dev/rootiest/color-tool/releases/latest) manually.
+Then run it from any location without installation:
+
+```bash
+# Make script executable
+chmod +x color-tool
+# Run script directly
+./color-tool --pick --output hex,rgb
+```
+
+However, this will not add the script to your `$PATH` or create a desktop entry,
+so you won't be able to launch it from the app menu or use it globally without specifying the path.
 
 ## 🛠 Usage
 
@@ -58,6 +84,7 @@ Options:
   --get-config   Print the current configuration
   --set-config   Update the configuration (e.g. --set-config desktop --copy)
   --reset-config Restore the configuration file to its default values
+  --check-deps   Check system dependencies and environment support
   --install      Install to ~/.local/share/ and symlink to ~/.local/bin/
   --help, -h     Show this help message
 ```