feat: initial blink-cmp-ssh implementation

Problem: the existing blink-cmp-sshconfig plugin uses a synchronous,
build-time Python scraping approach that requires uv and make to
generate a static Lua file.

Solution: implement a runtime, async blink.cmp source that parses
ssh_config keywords from man ssh_config and enum values from ssh -Q
queries, matching the architecture of blink-cmp-tmux and
blink-cmp-ghostty.

spec/helpers.lua

@@ -0,0 +1,54 @@
+local plugin_dir = vim.fn.getcwd()
+vim.opt.runtimepath:prepend(plugin_dir)
+
+if not package.loaded['blink.cmp.types'] then
+  package.loaded['blink.cmp.types'] = {
+    CompletionItemKind = {
+      Text = 1,
+      Method = 2,
+      Function = 3,
+      Constructor = 4,
+      Field = 5,
+      Variable = 6,
+      Class = 7,
+      Interface = 8,
+      Module = 9,
+      Property = 10,
+      Unit = 11,
+      Value = 12,
+      Enum = 13,
+      Keyword = 14,
+      Snippet = 15,
+      Color = 16,
+      File = 17,
+      Reference = 18,
+      Folder = 19,
+      EnumMember = 20,
+      Constant = 21,
+      Struct = 22,
+      Event = 23,
+      Operator = 24,
+      TypeParameter = 25,
+    },
+  }
+end
+
+local M = {}
+
+function M.create_buffer(lines, filetype)
+  local bufnr = vim.api.nvim_create_buf(false, true)
+  vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines or {})
+  if filetype then
+    vim.api.nvim_set_option_value('filetype', filetype, { buf = bufnr })
+  end
+  vim.api.nvim_set_current_buf(bufnr)
+  return bufnr
+end
+
+function M.delete_buffer(bufnr)
+  if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
+    vim.api.nvim_buf_delete(bufnr, { force = true })
+  end
+end
+
+return M