feat(subs): admin can correct a subscription's plan VERSION

A subscription froze its planVersionId at sale (reproducible pricing). There was
no way to move a sold sub onto a different VERSION of the SAME plan — needed when
an admin publishes v2 with different timeframes (e.g. mujor-naten-cdo-dite v1
"every day" → v2 "weekdays only") and wants an existing subscriber on it, or back
on v1.

Backend (PUT /api/subscriptions/:id):
- accept planVersionId; honored only with the subscription:plan permission
  (stronger than subscription:update — a plan-management action). Non-privileged
  caller sending a change → 403, not silently dropped.
- validated to belong to the sub's EXISTING planId (a different plan = a
  different price basis = a re-sale → 400).
- price/currency/period/planId stay frozen; only planVersionId moves. The swap is
  server-logged for audit (the row is mutable master data, not on the ledger).
  Past signed entry/exit events keep their own windowTariffVersionId, so history
  reprices identically — only future access uses the new version's windows.

Frontend (SubscriptionManager):
- pass the session user through the route (like RolesManager).
- admin-only "Versioni" picker in the edit modal: lists every version of the
  sub's plan by effective date + a timeframe summary (days + window, or 24/7),
  current pre-selected. The plan itself stays read-only. Sends planVersionId only
  when it changed.
- i18n: subs.version/versionHint/versionCurrent/versionOnlyOne/everyDay/allDay
  in both sq + en.

Verified on a writable DB copy: version changed, price + planId frozen,
cross-plan version rejected. Live DB untouched. build+lint 14/14.

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

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

@@ -409,6 +409,12 @@ export const sq = {
     count: "Sa",
     planNone: "— pa pagesë / falas —",
     planNoneAvail: "Asnjë plan i përcaktuar — admini duhet të krijojë një të parin.",
+    version: "Versioni",
+    versionCurrent: "aktual",
+    versionHint: "Zhvendos këtë abonent në një version tjetër të të njëjtit plan. Çmimi mbetet siç u faturua; ndryshon vetëm orari i lejuar nga këtu e tutje.",
+    versionOnlyOne: "vetëm një version i këtij plani",
+    everyDay: "çdo ditë",
+    allDay: "24/7 (pa orar)",
     quoting: "duke llogaritur…",
     quotePrompt: "zgjidh datën e mbarimit",
     quoteLine: "{{periods}} × {{unit}} · {{amount}} {{currency}}",