feat: human + relative dates; fix language/theme toggle stale-context

Dates were raw ISO on printed slips and time-only in the UI (a session from
two days ago showed just "10:48"). Make them human and day-relative. Also fix
a latent toggle bug surfaced while testing.

Dates:
- Printed tickets/receipts/subscription cards now show "19 Qershor 2026
  10:48:25" (Albanian month, 24h with seconds) instead of YYYY-MM-DD HH:MM.
  stamp() exported as formatStampSq so the shift Z-report shares it.
- Shift Z-report is now Albanian (Operatori/Nga/Deri/Para në dorë/Arka…),
  was English-only with ISO dates.
- Web sessions/logs/history show relative days: "Sot 10:48" / "Dje 17:33" /
  "17 Qershor 10:48" via formatRelativeDateTime(). Month names come from the
  i18n catalog (common.months), NOT Intl — the appliance browser's ICU lacks
  Albanian locale data and Intl silently falls back to English month names.

Toggle fix:
- The language + theme toggles read the active value from the TanStack Router
  context `user`, which is captured at route-resolution time and does not
  re-render on setUser. After one switch the highlight froze and the equality
  guard blocked switching back until a page refresh. Drive them off live state
  instead: language from i18n.language (useTranslation subscribes to
  languageChanged), theme from local useState. (Bug dated to 040c0ff.)

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

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

@@ -14,6 +14,24 @@ export const sq = {
     themeDark: "errët",
     themeLight: "çelët",
     theme: "Tema",
+    today: "Sot",
+    yesterday: "Dje",
+    // Month names (index 0 = January) — kept in the catalog because the appliance's
+    // browser ICU may lack Albanian locale data (Intl falls back to English).
+    months: [
+      "Janar",
+      "Shkurt",
+      "Mars",
+      "Prill",
+      "Maj",
+      "Qershor",
+      "Korrik",
+      "Gusht",
+      "Shtator",
+      "Tetor",
+      "Nëntor",
+      "Dhjetor",
+    ],
   },
   auth: {
     title: "Sistemi i Parkimit",
@@ -83,7 +101,6 @@ export const sq = {
     activeSessions: "Sesionet aktive",
     insideCount: "brenda",
     noActiveSessions: "Asnjë sesion aktiv.",
-    inAt: "në",
     openPayExit: "Hap pagesën / daljen",
     openBarrier: "Hap barrierën",
     openBarrierTitle: "Hap barrierën manualisht",