refactor: plan timeframes use a per-day-of-week picker (like the V2 tariff)

The timeframes model was a coarse weekday/weekend split, which couldn't express
"open Saturdays" or different rules on a specific day — and it didn't match the
V2 tariff, which already has a proper per-day-of-week picker (Hën–Die).

Replace PlanTimeframes { weekday, weekend } with { days[], fromMin, toMin }: the
allowed window applies only on the selected days (0=Sun..6=Sat; empty = every
day); on unselected days the subscriber parks free. A "night plan, free
weekends" is just days [Mon..Fri] with a 20:00→08:00 window — the exact case
from before, now expressible alongside any other day combination.

outOfWindowGap reworked to the days model (per-day membership test instead of
the weekend helper); the plans editor reuses the tariff composer's Mon-first
checkbox row and the shared tariff.dow0..6 labels. No production plans carry
timeframes yet (feature shipped today), so the shape changed directly with no
migration. Unit tests updated + extended (Saturday-only, every-day, weekday
night); 81 shared tests pass. Build+lint 12/12.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/lib/i18n/sq.ts

@@ -480,12 +480,12 @@ export const sq = {
     saved: "Plani u ruajt.",
     confirmRetire: "Të tërhiqet plani “{{name}}”? Nuk do të jetë më i shitshëm (historiku ruhet).",
     needWindow: "Shkruaj orare të vlefshme (HH:MM).",
+    needDays: "Zgjidh të paktën një ditë për intervalin.",
     restrictTimes: "Kufizo oraret e parkimit (tarifë kalimtare jashtë intervalit)",
-    weekdayWindow: "Ditë pune",
+    days: "Ditët",
+    window: "Intervali",
     enterAfter: "hyrje pas",
     exitBefore: "· dalje para",
-    weekend: "Fundjavë",
-    weekendAllDay: "gjithë ditën (pa kufizim)",
     grace: "Tolerancë",
     graceHint: "minuta tolerancë rreth kufijve të intervalit",
     timeframesHint: "Një skanim jashtë intervalit të lejuar tarifohet me tarifën normale kalimtare për minutat jashtë intervalit (hyrja e hershme shtyhet në dalje; dalja e vonuar bllokohet derisa paguhet).",