[idea] Add diagnostic jump keymaps ]d / [d to complement existing diagnostic config #131

What

Wire ]d / [d (next/prev diagnostic) to vim.diagnostic.goto_next() / vim.diagnostic.goto_prev() in options.lua.

Where

lua/config/options.lua — near the existing <leader>d diagnostic loclist keymap at line 12.

Why it matters

The config already invests in diagnostics: virtual text with ● prefix, float with rounded border and source labels, severity sorting, and <leader>d to populate the loclist. But there is no way to jump between diagnostics without opening the list first. ]d/[d would make diagnostic navigation as fluid as the existing ]g/[g (git hunks) and ]f/[f (functions) motions already in this config. The pattern is established; this fills the obvious gap.

Neovim 0.10+ ships vim.diagnostic.goto_next() and vim.diagnostic.goto_prev() natively — no extra plugins required.

Suggested implementation

In lua/config/options.lua near the existing <leader>d binding:

vim.keymap.set("n", "]d", function()
    vim.diagnostic.goto_next({ count = vim.v.count1 })
end, { desc = "Next diagnostic" })
vim.keymap.set("n", "[d", function()
    vim.diagnostic.goto_prev({ count = vim.v.count1 })
end, { desc = "Prev diagnostic" })

The count option makes 2]d skip to the second next diagnostic, consistent with how vim-sneak and other motion plugins handle counts in this config.