feat(core): add LSP reference navigation keymaps and drop octo.nvim import

lua/polish.lua

@@ -1,2 +1,18 @@
 -- This will run last in the setup process.
 -- Pure lua; anything that doesn't fit the normal config locations goes here.
+
+-- Snacks.keymap: LSP-aware keymaps, only applied to buffers with a client
+-- that supports the given method (which-key picks up the desc). ]] and [[
+-- cycle through the LSP references that snacks.words auto-highlights,
+-- complementing the core astrolsp `gd` / `gr` binds.
+local ok, snacks = pcall(require, "snacks")
+if ok then
+  snacks.keymap.set("n", "]]", function() snacks.words.jump(vim.v.count1, true) end, {
+    lsp = { method = "textDocument/documentHighlight" },
+    desc = "Next reference",
+  })
+  snacks.keymap.set("n", "[[", function() snacks.words.jump(-vim.v.count1, true) end, {
+    lsp = { method = "textDocument/documentHighlight" },
+    desc = "Previous reference",
+  })
+end