feat(nvim): sync CalDAV on startup via background jobstart

Runs vdirsyncer sync + ics-to-calendarim in a detached background job
on VimEnter so the calendar.vim cache stays fresh without blocking startup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nvim/init.lua

@@ -270,3 +270,14 @@ local function toggle_pim()
 end
 
 vim.keymap.set("n", "x", toggle_pim, { silent = true })
+
+-- ── CalDAV background sync on startup ────────────────────────────────────────
+vim.api.nvim_create_autocmd("VimEnter", {
+    once     = true,
+    callback = function()
+        vim.fn.jobstart(
+            { "sh", "-c", "vdirsyncer sync && ics-to-calendarim" },
+            { detach = true }
+        )
+    end,
+})