docs(web): add JetBrains IDE integration guide (LSP4IJ)

AGENTS.md

@@ -58,6 +58,7 @@ Agents should remind humans of this when possible.
 - `packages/web/src/routes/docs/integrations/emacs/+page.md`: Emacs setup using `harper-ls`, plus optional and common config tweaks.
 - `packages/web/src/routes/docs/integrations/zed/+page.md`: Zed extension entry point and link to canonical extension README.
 - `packages/web/src/routes/docs/integrations/sublime-text/+page.md`: Sublime Text setup with `harper-ls` and LSP package configuration.
+- `packages/web/src/routes/docs/integrations/jetbrains/+page.md`: JetBrains IDE setup via the LSP4IJ plugin's built-in `harper-ls` support.
 - `packages/web/src/routes/docs/harperjs/introduction/+page.md`: `harper.js` mission, package overview, and installation starting point.
 - `packages/web/src/routes/docs/harperjs/linting/+page.md`: Core `harper.js` lint workflow and linter usage patterns.
 - `packages/web/src/routes/docs/harperjs/spans/+page.md`: Explains span objects and how to use them to locate/handle lint ranges.

packages/web/src/routes/docs/integrations/jetbrains/+page.md

@@ -0,0 +1,21 @@
+---
+title: JetBrains IDEs
+---
+
+You can use [`harper-ls`](./language-server) in any IDE built on the IntelliJ Platform — IntelliJ IDEA, WebStorm, PyCharm, Rider, GoLand, RustRover, CLion, PhpStorm, RubyMine, and more — through the community [LSP4IJ](https://plugins.jetbrains.com/plugin/23257-lsp4ij) plugin, which ships with `harper-ls` support built in. No Harper-specific plugin is required.
+
+## Required Setup
+
+Make sure you have `harper-ls` installed and available on your `PATH`. You can do this using the [supported installation methods](./language-server#Installation).
+
+Install [LSP4IJ](https://plugins.jetbrains.com/plugin/23257-lsp4ij) from `Settings/Preferences > Plugins > Marketplace`, then search for "LSP4IJ" and click "Install".
+
+## Enabling `harper-ls`
+
+LSP4IJ includes a predefined entry for `harper-ls` under `Settings/Preferences > Languages & Frameworks > Language Servers`. Enable it there, or add `harper-ls` as a user-defined language server pointing at your installed binary if your version of LSP4IJ doesn't list it yet.
+
+For the exact, up-to-date steps and screenshots, see [LSP4IJ's `harper-ls` documentation](https://github.com/redhat-developer/lsp4ij/blob/main/docs/user-defined-ls/harper-ls.md), since that page is maintained by the LSP4IJ project and may change independently of Harper.
+
+## Configuration
+
+`harper-ls` is configured the same way regardless of editor. See the [configuration section](./language-server#Configuration) of our `harper-ls` documentation for the full list of options, including dialect, dictionaries, and which linters to enable.

packages/web/vite.config.ts

@@ -121,6 +121,10 @@ export default defineConfig(async () => {
 											title: 'Sublime Text',
 											to: '/docs/integrations/sublime-text',
 										},
+										{
+											title: 'JetBrains IDEs',
+											to: '/docs/integrations/jetbrains',
+										},
 									],
 								},
 								{