feat(cli): add Shellsavers terminal animations (#14167)

Co-authored-by: Carlo Sala <carlosalag@protonmail.com>

README.md

@@ -45,6 +45,7 @@ Twitter), and join us on [Discord](https://discord.gg/ohmyzsh).
     - [Using Plugins](#using-plugins)
   - [Themes](#themes)
     - [Selecting A Theme](#selecting-a-theme)
+  - [Shellsavers](#shellsavers)
   - [FAQ](#faq)
 - [Advanced Topics](#advanced-topics)
   - [Advanced Installation](#advanced-installation)
@@ -241,6 +242,33 @@ If you only know which themes you don't like, you can add them similarly to an i
 ZSH_THEME_RANDOM_IGNORED=(pygmalion tjkirch_mod)
 ```
 
+### Shellsavers
+
+Give your terminal a little downtime with `omz shellsaver`—our playful name for
+terminal screensavers. The aquarium is the default; choose another scene to change the mood:
+
+```zsh
+omz shellsaver                 # A quiet aquarium full of sea shells
+omz shellsaver logo            # The updater's rainbow logo, bouncing around
+omz shellsaver hermit          # A slightly lost hermit crab
+omz shellsaver party           # A rainbow stage and a dancing crowd
+```
+
+Press any key or Ctrl-C to return to your shell. Screensavers run only when invoked
+and restore the terminal when they exit. No plugin or configuration change is needed.
+Use `omz help` to discover the command, and Tab to complete scene names and options.
+
+```zsh
+omz shellsaver aquarium --seconds 30  # Stop automatically after 30 seconds
+omz shellsaver logo --mono            # Use the terminal's foreground color
+omz shellsaver --list                 # List scenes (aquarium is the default)
+omz shellsaver --help                 # Show all scenes and options
+```
+
+Requires Zsh 5.8 or newer, `stty`, and an xterm-compatible terminal with alternate-screen
+support. No additional animation package is required. `NO_COLOR` is respected.
+A window of at least 49 columns by 18 rows is recommended.
+
 ### FAQ
 
 If you have some more questions or issues, you might find a solution in our