docs: remove dead Zsh plugin integration

The zsh-pythinker-code repo returns 404 under both the current owner (elkaix)
and the former handle (mohamed-elkholy95), so the section linked only to dead
URLs. Remove it; the page keeps its intro for future integrations.

The remaining mohamed-elkholy95 references in feedback_repo.py and its tests are
the legacy migrate-from owner (rewritten to Pythoughts-labs/pythinker-code) and
are intentionally left unchanged.

Author: elkaix

docs/en/guides/integrations.md

@@ -1,36 +1,3 @@
 # Integrations with Tools
 
 Besides using in the terminal and IDEs, Pythinker Code can also be integrated with other tools.
-
-## Zsh plugin
-
-[zsh-pythinker-code](https://github.com/mohamed-elkholy95/zsh-pythinker-code) is a Zsh plugin that lets you quickly switch to Pythinker Code in Zsh.
-
-**Installation**
-
-If you use Oh My Zsh, you can install it like this:
-
-```sh
-git clone https://github.com/mohamed-elkholy95/zsh-pythinker-code.git \
-  ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/pythinker-code
-```
-
-Then add the plugin in `~/.zshrc`:
-
-```sh
-plugins=(... pythinker-code)
-```
-
-Reload the Zsh configuration:
-
-```sh
-source ~/.zshrc
-```
-
-**Usage**
-
-After installation, press `Ctrl-X` in Zsh to quickly switch to Pythinker Code without manually typing the `pythinker` command.
-
-::: tip
-If you use other Zsh plugin managers (like zinit, zplug, etc.), please refer to the [zsh-pythinker-code repository](https://github.com/mohamed-elkholy95/zsh-pythinker-code) README for installation instructions.
-:::