fix: unify day boundaries on device-local time, JSON import preview parity

- Limits/streaks/greeting now use device-local days (was hardcoded Europe/London),
  matching dashboard metrics; label copy updated
- JSON imports now go through the same preview/duplicate-detection modal as Excel

src/components/ImportPreviewModal.tsx

@@ -37,7 +37,9 @@ export function ImportPreviewModal({
         >
           <div className="mb-5 flex items-start justify-between gap-4">
             <div>
-              <p className="text-sm font-medium uppercase tracking-[0.18em] text-pink-100">Excel import</p>
+              <p className="text-sm font-medium uppercase tracking-[0.18em] text-pink-100">
+                {preview.fileName.toLowerCase().endsWith(".json") ? "JSON import" : "Excel import"}
+              </p>
               <h2 id="import-preview-title" className="mt-1 text-3xl font-semibold tracking-tight text-white">
                 Preview rows
               </h2>

src/components/LimitsSettingsForm.tsx

@@ -142,7 +142,7 @@ export function LimitsSettingsForm({ limits, check, saving, onSave }: LimitsSett
             value={canInput}
             onChange={(event) => handleCanInputChange(event.target.value)}
           />
-          <span className="text-xs text-slate-500">Leave empty to remove. Counts use BST calendar days.</span>
+          <span className="text-xs text-slate-500">Leave empty to remove. Counts use device-local calendar days.</span>
         </label>
 
         <label className="grid gap-2 text-sm">
@@ -170,7 +170,7 @@ export function LimitsSettingsForm({ limits, check, saving, onSave }: LimitsSett
           value={stopInput}
           onChange={(event) => setStopInput(event.target.value)}
         />
-        <span className="text-xs text-slate-500">Europe/London (BST/GMT). Leave empty to remove.</span>
+        <span className="text-xs text-slate-500">Your device's local time. Leave empty to remove.</span>
       </label>
 
       {previewParts.length ? (

src/components/views/SettingsView.tsx

@@ -61,7 +61,7 @@ export function SettingsView({
   return (
     <div className="grid gap-4 xl:grid-cols-[1fr_0.8fr]">
       <div className="grid content-start gap-4">
-        <AppCard title="Limits" subtitle="Personal caps for cans, spend, and stop time (BST)">
+        <AppCard title="Limits" subtitle="Personal caps for cans, spend, and stop time (local time)">
           <LimitsSettingsForm
             limits={userLimits}
             check={limitCheck}