Feature/jetbrains ide companion

[SoLoHiC]

TLDR

Really liked Gemini-CLI and can't wait for it working within IntelliJ IDEA and other JetBrains IDE. So I took a few days during this vacation working on this plugin(, well, most of the code is actually written by Gemini itself and I'm just co-piloting along , dealing with a few tricky issues about how the MCP's streamable http transport works in Kotlin and making sure its UI works as expected.

This PR creates a JetBrains plugin providing similar features like the VS Code companion extension does. As I've tested locally, it should basically follow the https://github.com/google-gemini/gemini-cli/blob/main/docs/ide-integration/ide-companion-spec.md.

Dive Deeper

All code changes can be found under packages/jebrains-ide-companion/ .

Reviewer Test Plan

the way i tested it after pulling the code:

1. go to the project root directory
2. Build the plugin and the customized gemini-cli using npm run build
3. In your JetBrains IDE, go to Settings > Plugins > Install Plugin from Disk
4. Select the generated plugin ZIP file from packages/jebrains-ide-companion/build/distributions/
5. go back to the project root directory, install the customized gemini-cli using npm install -g .
6. run gemini in the JetBrains IDE's Terminal window
7. run /ide status within gemini-cli, should be showing ' Connected to IntelliJ IDEA 2025.2'

And also, other main features like the VSCode extension provided can be test too. Demo result below:

Testing Matrix

	🍏	🪟	🐧
npm run	✅	❓	❓
npx	❓	❓	❓
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-

Linked issues / bugs

I see there already is an issue created by alcarraz, (https://github.com/google-gemini/gemini-cli/issues/9273) skeshive , please take a look at this and thanks for your work on the VS Code extension.