feat: migrate from lazy.nvim to vim.pack

Replace lazy.nvim plugin manager with Neovim 0.12's native vim.pack API.
All plugin config files rewritten from lazy.nvim spec tables to imperative
require/setup format with explicit vim.keymap.set() calls.

Key changes:
- vim.pack.add() with ~53 plugins in init.lua
- blink.cmp/pairs/download pinned to version tags (vim.version.range)
- PackChanged autocmd for markdown-preview build hook
- Ordered requires: colorscheme → ui → treesitter → completion → lsp → rest
- Plugin setup guards (gitsigns, which-key, blink.cmp) handle deferred
  plugin/ file loading correctly

Net reduction: ~438 lines across 13 files.

1 files changed, 74 insertions, 97 deletions

diff --git a/home/.config/nvim/lua/plugins/completion.lua b/home/.config/nvim/lua/plugins/completion.lua
index 0310923..df24a5d 100644
--- a/home/.config/nvim/lua/plugins/completion.lua
+++ b/home/.config/nvim/lua/plugins/completion.lua
@@ -1,109 +1,86 @@
-return {
-  {
-    "saghen/blink.compat",
-    opts = {},
+require("blink.compat").setup({})
+
+require("blink.cmp").setup({
+  keymap = {
+    preset = "cmdline",
+    ["<CR>"] = { "accept", "fallback" },
   },
-  {
-    "saghen/blink.cmp",
-    dependencies = {
-      "rafamadriz/friendly-snippets",
-      "fang2hou/blink-copilot",
-      "rcarriga/cmp-dap",
-      "xzbdmw/colorful-menu.nvim",
-    },
-    opts = {
-      keymap = {
-        preset = "cmdline",
-        ["<CR>"] = { "accept", "fallback" },
-      },
-      appearance = {
-        use_nvim_cmp_as_default = true,
-      },
-      completion = {
-        menu = {
-          draw = {
-            -- treesitter = { "lsp" },
-            -- We don't need label_description now because label and label_description are already
-            -- combined together in label by colorful-menu.nvim.
-            columns = { { "kind_icon" }, { "label", gap = 1 } },
-            components = {
-              label = {
-                text = function(ctx)
-                  return require("colorful-menu").blink_components_text(ctx)
-                end,
-                highlight = function(ctx)
-                  return require("colorful-menu").blink_components_highlight(
-                    ctx
-                  )
-                end,
-              },
-            },
-          },
-        },
-        list = {
-          selection = {
-            preselect = function()
-              return not require("blink.cmp").snippet_active({ direction = 1 })
+  appearance = {
+    use_nvim_cmp_as_default = true,
+  },
+  completion = {
+    menu = {
+      draw = {
+        columns = { { "kind_icon" }, { "label", gap = 1 } },
+        components = {
+          label = {
+            text = function(ctx)
+              return require("colorful-menu").blink_components_text(ctx)
+            end,
+            highlight = function(ctx)
+              return require("colorful-menu").blink_components_highlight(ctx)
             end,
           },
         },
-        documentation = { auto_show = true },
-      },
-      signature = {
-        enabled = true,
-        trigger = {
-          enabled = true,
-          show_on_keyword = true,
-          show_on_insert = true,
-        },
       },
-      sources = {
-        default = { "lazydev", "lsp", "copilot", "snippets", "path", "buffer" },
-        per_filetype = {
-          ["dap-repl"] = { "dap" },
-        },
-        providers = {
-          path = {
-            opts = {
-              get_cwd = vim.fn.getcwd,
-            },
-          },
-          copilot = {
-            name = "copilot",
-            module = "blink-copilot",
-            score_offset = 100,
-            async = true,
-          },
-          lazydev = {
-            name = "LazyDev",
-            module = "lazydev.integrations.blink",
-            -- make lazydev completions top priority (see `:h blink.cmp`)
-            score_offset = 100,
-          },
-          dap = { name = "dap", module = "blink.compat.source" },
-        },
+    },
+    list = {
+      selection = {
+        preselect = function()
+          return not require("blink.cmp").snippet_active({ direction = 1 })
+        end,
       },
     },
+    documentation = { auto_show = true },
   },
-  {
-    "saghen/blink.pairs",
-    version = "*",
-    dependencies = "saghen/blink.download",
-    opts = {
-      mappings = {
-        disabled_filetypes = {},
-      },
-      highlights = {
-        groups = {
-          "BlinkIndentOrange",
-          "BlinkIndentViolet",
-          "BlinkIndentBlue",
-          "BlinkIndentRed",
-          "BlinkIndentCyan",
-          "BlinkIndentYellow",
-          "BlinkIndentGreen",
+  signature = {
+    enabled = true,
+    trigger = {
+      enabled = true,
+      show_on_keyword = true,
+      show_on_insert = true,
+    },
+  },
+  sources = {
+    default = { "lazydev", "lsp", "copilot", "snippets", "path", "buffer" },
+    per_filetype = {
+      ["dap-repl"] = { "dap" },
+    },
+    providers = {
+      path = {
+        opts = {
+          get_cwd = vim.fn.getcwd,
         },
       },
+      copilot = {
+        name = "copilot",
+        module = "blink-copilot",
+        score_offset = 100,
+        async = true,
+      },
+      lazydev = {
+        name = "LazyDev",
+        module = "lazydev.integrations.blink",
+        score_offset = 100,
+      },
+      dap = { name = "dap", module = "blink.compat.source" },
+    },
+  },
+})
+
+require("blink.pairs").setup({
+  mappings = {
+    disabled_filetypes = {},
+  },
+  highlights = {
+    groups = {
+      "BlinkIndentOrange",
+      "BlinkIndentViolet",
+      "BlinkIndentBlue",
+      "BlinkIndentRed",
+      "BlinkIndentCyan",
+      "BlinkIndentYellow",
+      "BlinkIndentGreen",
     },
   },
-}
+})