feat: add unified LSP tool

[RhysSullivan]

Summary

Playing around with this, originally came from oh-my-opencode that makes these each individual tools, this unifies them into one tool. Still not sure I like the structure of it, feels like it dumps a lot into context

AI generated below:

Add a new lsp tool that exposes LSP functionality to the model, enabling intelligent code operations across all supported languages.

Supported Actions

• hover: Get type info at position
• definition: Jump to symbol definition
• references: Find all usages
• documentSymbols: Get file symbol outline
• workspaceSymbols: Search symbols by name
• diagnostics: Get errors/warnings
• prepareRename: Check if rename is valid
• rename: Rename symbol across workspace (auto-applies edits)
• codeActions: Get available code actions (quickfixes, refactors)
• codeActionResolve: Apply a code action

Key Features

• Works with all 25+ LSP servers already configured in opencode (TypeScript, Go, Rust, Python, etc.)
• Automatically routes to the correct LSP server based on file extension
• Rename operations automatically apply workspace edits across all affected files
• Code actions include relevant diagnostics for quickfixes like "Remove unused import"

Example Usage

{
  "action": "rename",
  "filePath": "/path/to/file.ts",
  "line": 10,
  "character": 5,
  "newName": "newFunctionName"
}