feat: proper Go setup with gopls, formatters, and debugger

- Add Mason bin to Neovim PATH so formatters/linters are discoverable
- Add Mason ensure_installed for gofumpt, goimports, delve + stylua, black, yamlfmt
- Add Go filetype settings (tabs, tabwidth=4) in golang.lua
- Remove redundant Go keymaps — existing LSP and vim-test keymaps already cover everything

Co-Authored-By: Claude <noreply@anthropic.com>

lua/user/lsp.lua

@@ -1,5 +1,18 @@
--- 1. Setup Mason first
-require("mason").setup()
+-- 1. Setup Mason first (LSPs + tools)
+require("mason").setup({
+    ensure_installed = {
+        -- Go toolchain
+        "gofumpt",
+        "goimports",
+        "delve",
+        -- Lua
+        "stylua",
+        -- Python
+        "black",
+        -- YAML
+        "yamlfmt",
+    },
+})
 require("mason-lspconfig").setup({
     -- Remove "jdtls" from here to prevent the 'enable' (nil value) crash
     ensure_installed = {

lua/user/lsp_servers/golang.lua

@@ -1,3 +1,13 @@
+-- Go filetype settings (Go uses tabs, not spaces)
+vim.api.nvim_create_autocmd("FileType", {
+    pattern = { "go", "gomod", "gowork", "gotmpl" },
+    callback = function()
+        vim.opt_local.expandtab = false
+        vim.opt_local.tabstop = 4
+        vim.opt_local.shiftwidth = 4
+    end,
+})
+
 -- Go LSP configuration
 -- Uses gopls installed via Mason
 
@@ -35,37 +45,4 @@ vim.lsp.config("gopls", {
     },
 })
 
--- Go-specific LSP attach handlers
-vim.api.nvim_create_autocmd("LspAttach", {
-    callback = function(args)
-        local client = vim.lsp.get_client_by_id(args.data.client_id)
-        if client and client.name == "gopls" then
-            local bufnr = args.buf
-
-            -- Go: organize imports on demand
-            vim.keymap.set("n", "<leader>gi", function()
-                vim.lsp.buf.code_action({
-                    context = { only = { "source.organizeImports" } },
-                    apply = true,
-                })
-            end, { buffer = bufnr, desc = "Go: Organize imports" })
-
-            -- Go: toggle test file
-            vim.keymap.set("n", "<leader>gt", function()
-                local fname = vim.fn.expand("%")
-                if fname:match("_test%.go$") then
-                    vim.cmd("edit " .. fname:gsub("_test%.go$", ".go"))
-                else
-                    vim.cmd("edit " .. fname:gsub("%.go$", "_test.go"))
-                end
-            end, { buffer = bufnr, desc = "Go: Toggle test file" })
-
-            -- Go: run current file's tests
-            vim.keymap.set("n", "<leader>gr", function()
-                vim.cmd("!go test ./...")
-            end, { buffer = bufnr, desc = "Go: Run tests" })
-        end
-    end,
-})
-
 vim.lsp.enable("gopls")

lua/user/options.lua

@@ -70,3 +70,6 @@ opt.scrolloff = 8
 -- minimal number of screen columns either side of cursor if wrap is `false`
 opt.sidescrolloff = 8
 
+-- Add Mason's bin directory to PATH (LSPs, formatters, linters, debuggers)
+vim.env.PATH = vim.fn.expand("~/.local/share/nvim/mason/bin") .. ":" .. (vim.env.PATH or "")
+