docs: Update Node.js requirement from 18 to 20

Update CLI documentation to reflect the new Node.js 20 minimum version
requirement, aligning with the pkg target updates in #8994.

Co-authored-by: nate <[email protected]>

Generated with [Continue](https://continue.dev)

Co-Authored-By: Continue <[email protected]>

Author: continue[bot]

docs/cli/install.mdx

@@ -15,7 +15,7 @@ sidebarTitle: "Install"
 ></iframe>
 
 <Info>
-  Make sure you have [Node.js 18 or higher
+  Make sure you have [Node.js 20 or higher
   installed](https://nodejs.org/en/download/).
 </Info>
 

docs/cli/overview.mdx

@@ -19,7 +19,7 @@ sidebarTitle: "Overview"
 
 Prerequisites:
 
-- [Node.js 18 or newer](https://nodejs.org/en/download/)
+- [Node.js 20 or newer](https://nodejs.org/en/download/)
 - A [Continue Mission Control](https://hub.continue.dev) account (recommended) or local configuration
 
 ```bash npm

docs/guides/cli.mdx

@@ -13,7 +13,7 @@ It provides a battle-tested agent loop so you can simply plug in your model, rul
 ## Quick start
 
 <Info>
-  Make sure you have [Node.js 18 or higher
+  Make sure you have [Node.js 20 or higher
   installed](https://nodejs.org/en/download/).
 </Info>