feat(ai): add NickvanDyke/opencode.nvim (#1654)

* feat(ai): add `NickvanDyke/opencode.nvim`

* Update lua/astrocommunity/ai/opencode-nvim/README.md

* feat: add dependency

---------

Co-authored-by: Uzair Aftab <48220549+Uzaaft@users.noreply.github.com>
Co-authored-by: Uzair Aftab <git@uzaaft.me>

Author: ALameLlama

lua/astrocommunity/ai/opencode-nvim/README.md

@@ -0,0 +1,6 @@
+# NickvanDyke/opencode.nvim
+
+Integrate the opencode AI assistant with Neovim — streamline editor-aware research, reviews, and requests.
+
+**Repository**: <https://github.com/NickvanDyke/opencode.nvim>
+

lua/astrocommunity/ai/opencode-nvim/init.lua

@@ -0,0 +1,64 @@
+return {
+  "NickvanDyke/opencode.nvim",
+  dependencies = {
+    { "folke/snacks.nvim", opts = { input = { enabled = true } } },
+  },
+  specs = {
+    {
+      "AstroNvim/astrocore",
+      ---@param opts AstroCoreOpts
+      opts = function(_, opts)
+        local maps = assert(opts.mappings)
+        local prefix = "<Leader>o"
+        maps.n[prefix] = { desc = require("astroui").get_icon("OpenCode", 1, true) .. "OpenCode" }
+        maps.n[prefix .. "t"] = {
+          function() require("opencode").toggle() end,
+          desc = "Toggle embedded",
+        }
+        maps.n[prefix .. "a"] = {
+          function() require("opencode").ask "@cursor: " end,
+          desc = "Ask about this",
+        }
+        maps.n[prefix .. "+"] = {
+          function() require("opencode").prompt("@buffer", { append = true }) end,
+          desc = "Add buffer to prompt",
+        }
+        maps.n[prefix .. "e"] = {
+          function() require("opencode").prompt "Explain @cursor and its context" end,
+          desc = "Explain this code",
+        }
+        maps.n[prefix .. "n"] = {
+          function() require("opencode").command "session_new" end,
+          desc = "New session",
+        }
+        maps.n[prefix .. "s"] = {
+          function() require("opencode").select() end,
+          desc = "Select prompt",
+        }
+        maps.n["<S-C-u>"] = {
+          function() require("opencode").command "messages_half_page_up" end,
+          desc = "Messages half page up",
+        }
+        maps.n["<S-C-d>"] = {
+          function() require("opencode").command "messages_half_page_down" end,
+          desc = "Messages half page down",
+        }
+
+        maps.v[prefix] = { desc = require("astroui").get_icon("OpenCode", 1, true) .. "OpenCode" }
+        maps.v[prefix .. "a"] = {
+          function() require("opencode").ask "@selection: " end,
+          desc = "Ask about selection",
+        }
+        maps.v[prefix .. "+"] = {
+          function() require("opencode").prompt("@selection", { append = true }) end,
+          desc = "Add selection to prompt",
+        }
+        maps.v[prefix .. "s"] = {
+          function() require("opencode").select() end,
+          desc = "Select prompt",
+        }
+      end,
+    },
+    { "AstroNvim/astroui", opts = { icons = { OpenCode = "" } } },
+  },
+}