chore(format): migrate from biome to oxfmt

oxfmt (already vendored via the vite-plus pack) replaces biome for the
format gate over the same file scope. Config: useTabs to match the
repo; otherwise oxfmt defaults, so this includes a one-time reformat
of the covered non-src files (sorted package.json keys, denser
prettier-style wrapping). Adds a 'format' write script alongside
format:check.

Author: chhoumann

.oxfmtrc.json

@@ -0,0 +1,5 @@
+{
+	"$schema": "./node_modules/oxfmt/configuration_schema.json",
+	"useTabs": true,
+	"ignorePatterns": []
+}