refactor(fitness): adopt t.key / t[expr] syntax across fitness pages

22 files migrated from t('key', lang) function calls to direct lookups
on a derived dictionary alias: const t = $derived(m[lang]) once per
file, then t.start_period or t[card.labelKey] at the call sites.

Cleaner read at the point of use, one less argument threaded through,
and TypeScript narrows on every key access (so a typo in a literal
key now errors at the call site, not silently falls back to the key
string).

The codemod handles both ways `lang` can enter scope — derived from
the URL via detectFitnessLang, or destructured from $props() (single
or multi-line). One file aliased the i18n table to `messages` to
avoid collision with a local `const m = data.measurement`.

The deprecated `t(key, lang)` function still exists in fitnessI18n.ts
for any remaining out-of-tree call sites — can be deleted once
nothing imports it.

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "homepage",
-	"version": "1.54.0",
+	"version": "1.54.1",
 	"private": true,
 	"type": "module",
 	"scripts": {