feat(plugins): setup codeium and copilot AI integrations

lua/plugins/ai/codeium.lua

@@ -0,0 +1,13 @@
+return {
+  {
+    "jcdickinson/codeium.nvim",
+    cond = EcoVim.plugins.ai.codeium.enabled,
+    event = "InsertEnter",
+    cmd = "Codeium",
+    dependencies = {
+      "nvim-lua/plenary.nvim",
+      "hrsh7th/nvim-cmp",
+    },
+    config = true,
+  },
+}

lua/plugins/ai/copilot-chat.lua

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+return {
+  {
+    "CopilotC-Nvim/CopilotChat.nvim",
+    event = "VeryLazy",
+    opts = {
+      show_help = "no",
+      prompts = {
+        Explain = "Explain how it works.",
+        Review = "Review the following code and provide concise suggestions.",
+        Tests = "Briefly explain how the selected code works, then generate unit tests.",
+        Refactor = "Refactor the code to improve clarity and readability.",
+      },
+    },
+    build = function()
+      vim.defer_fn(function()
+        vim.cmd("UpdateRemotePlugins")
+        vim.notify("CopilotChat - Updated remote plugins. Please restart Neovim.")
+      end, 3000)
+    end,
+    keys = {
+      { "<leader>ccb", ":CopilotChatBuffer<cr>",      desc = "CopilotChat - Buffer" },
+      { "<leader>cce", "<cmd>CopilotChatExplain<cr>", desc = "CopilotChat - Explain code" },
+      { "<leader>cct", "<cmd>CopilotChatTests<cr>",   desc = "CopilotChat - Generate tests" },
+      {
+        "<leader>ccT",
+        "<cmd>CopilotChatVsplitToggle<cr>",
+        desc = "CopilotChat - Toggle Vsplit", -- Toggle vertical split
+      },
+      {
+        "<leader>ccv",
+        ":CopilotChatVisual",
+        mode = "x",
+        desc = "CopilotChat - Open in vertical split",
+      },
+      {
+        "<leader>ccc",
+        ":CopilotChatInPlace<cr>",
+        mode = { "n", "x" },
+        desc = "CopilotChat - Run in-place code",
+      },
+      {
+        "<leader>ccf",
+        "<cmd>CopilotChatFixDiagnostic<cr>", -- Get a fix for the diagnostic message under the cursor.
+        desc = "CopilotChat - Fix diagnostic",
+      },
+    }
+  },
+}

lua/plugins/ai/copilot.lua

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+return {
+  {
+    "zbirenbaum/copilot.lua",
+    cond = EcoVim.plugins.ai.copilot.enabled,
+    lazy = false,
+    opts = {
+      suggestion = { enabled = false },
+      panel = { enabled = false },
+    }
+  },
+}