docs: add ENOSPC file watcher limit troubleshooting

[Copilot]

Linux systems crash Vite with ENOSPC: System limit for number of file watchers reached when projects contain many files (e.g., large asset directories). The error message provides no guidance on resolution.

Changes

Added troubleshooting section documenting three solutions:

• Increase system limit: Commands to check and modify fs.inotify.max_user_watches (temporary and persistent)
• Exclude directories: Using server.watch.ignored to skip monitoring large asset folders
• Use polling: Fallback with server.watch.usePolling when native file watching isn't viable

export default defineConfig({
  server: {
    watch: {
      ignored: ['**/storage/**', '**/large-asset-folder/**'],
    },
  },
})

Links to server configuration docs and chokidar performance considerations included.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Too many files in cwd will crash Vite on Linux</issue_title>
<issue_description>### Describe the bug

Linux has a default limit of file watchers (around 10K). If you happen to have 1M images in working directory, Vite server will crash.

Workaround is to add folders to server.watch.ignore. However, the error messages should be more instructive.

Reproduction

https://github.com/guoyunhe/vite-file-watcher-limit

Steps to reproduce

git clone git@github.com:guoyunhe/vite-file-watcher-limit.git
cd vite-file-watcher-limit
pnpm i
pnpm dev

Wait for 10s and it will probably crash

System Info

System:
    OS: Linux 6.18 openSUSE Tumbleweed 20260106
    CPU: (12) x64 AMD Ryzen 5 5600X 6-Core Processor
    Memory: 19.64 GB / 31.27 GB
    Container: Yes
    Shell: 5.3.9 - /bin/bash
  Binaries:
    Node: 22.21.1 - /usr/bin/node
    Yarn: 1.22.22 - /usr/bin/yarn
    npm: 10.9.4 - /usr/bin/npm
    pnpm: 10.20.0 - /home/guo/.local/share/pnpm/pnpm
    Deno: 2.4.5 - /usr/bin/deno
  Browsers:
    Chromium: 143.0.7499.169
    Firefox: 146.0.1
    Firefox Developer Edition: 146.0.1
  npmPackages:
    @vitejs/plugin-react: ^5.1.1 => 5.1.2 
    vite: ^7.2.4 => 7.3.1

Used Package Manager

pnpm

Logs

Error: ENOSPC: System limit for number of file watchers reached, watch '/home/guo/git/vite-file-watcher-limit/storage/file-319871.jpg'

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.</issue_description>

<agent_instructions>Add a section to troubleshooting docs. mention fs.inotify.max_user_watches and server.watcher.ignore and server.watcher.usePolling</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Too many files in cwd will crash Vite on Linux #21384

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