feat(lsp): add terraformls, rust_analyzer, configure nixd

Add support for Terraform and Rust language servers, and configure nixd
with home-manager options for better Nix completions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

dots/.config/nvim/after/plugin/lspconfig.lua

@@ -65,8 +65,26 @@ local servers = {
     },
   },
   -- marksman = {},
-  nixd = {},
+  -- TODO: This completion ain't working yet
+  nixd = {
+    nixpkgs = {
+      expr = "import <nixpkgs> { }",
+    },
+    formatting = {
+      command = { "nixfmt" },
+    },
+    options = {
+      home_manager = {
+        expr = '(builtins.getFlake "/home/hektor/.config/home-manager").homeConfigurations.work.options',
+      },
+    },
+  },
   pyright = {},
+  rust_analyzer = {
+    settings = {
+      ["rust-analyzer"] = {},
+    },
+  },
   -- tsserver = {},
   svelte = {
     plugin = {
@@ -76,6 +94,7 @@ local servers = {
     },
   },
   tailwindcss = {},
+  terraformls = {},
   vtsls = {
   -- ts_ls = {},
   vtsls = {