fix nvim: upgrade avante.nvim and update providers format. and fix ollama api key

Provider configuration migration guide: <https://github.com/yetone/avante.nvim/wiki/Provider-configuration-migration-guide>

dot_config/nvim/exact_lua/exact_plugins/exact_components/ai.lua.tmpl

@@ -30,7 +30,7 @@ return {
       { "<C-A-i>", "<cmd>AvanteToggle<cr>", desc = "Avante Chat Toggle" },
     },
     opts = {
-      provider = "ollama",
+      providers = {
         ollama = {
           {{ if .ollamaKey -}}
           api_key_name = "OLLAMA_API_KEY",
@@ -38,8 +38,15 @@ return {
           endpoint = {{ .ollamaUrl | quote }},
           model = "qwen2.5-coder:7b",
           disable_tools = true, -- Open-source models often do not support tools.
+
+          -- Fix: Always show `ollama: API key not set, continuing without authentication`
+          parse_api_key = function()
+            return vim.env.OLLAMA_API_KEY
+          end,
+        },
       },
 
+      provider = "ollama",
       behaviour = {
         auto_suggestions = false, -- Experimental stage
         auto_set_highlight_group = true,