[FEATURE]: support oxlint lsp

[Eric162]

Describe the enhancement you want to request

OpenCode already integrates with LSP servers to surface diagnostics. It would be great to add built-in support for Oxlint’s LSP mode (oxlint --lsp) so JS/TS projects can get fast lint diagnostics.

Why

• Oxlint is extremely fast and widely used for JS/TS linting.
• oxlint --lsp can publish diagnostics directly over stdio.

Proposed behavior

• Add a built-in oxlint LSP server entry with the JS/TS + framework extensions it supports (e.g. .js, .ts, .tsx, .vue, .astro, .svelte).
• Only enable it when oxlint is already installed (no auto-download).
• Keep existing LSP server selection configurable via lsp config (users decide which servers to enable/disable).

Notes

• This is separate from ESLint: both can coexist; users can disable either via config.

[github-actions[bot]]

This issue might be a duplicate of existing issues. Please check:

• #1822: [Biome LSP support] - Similar feature request for adding another linter's LSP to OpenCode
• #5535: [FSharp LSP] - Similar pattern for adding built-in LSP server support with conditional enablement

Both show that OpenCode has a pattern for integrating additional LSP servers as built-in options that are only enabled when the tool is installed.