feat(subscription): rename permit→subscription + monthly pricing

The "permit/lejet" feature is really a subscription. Full rename of the
mutable master data, plus a recurring monthly price.

- DB (migration 0004, data-preserving ALTER RENAME): permits→subscriptions,
  permit_credentials/_plates→subscription_*, sessions.permit_id→subscription_id.
- Pricing: per-subscription priceMinor + period(monthly) + currency, with a
  site default (site_config.subscription_monthly_price_minor) pre-filling the form.
- Server: subscription-flow.ts (SubscriptionFlow), routes/subscriptions.ts
  (/api/subscriptions). Web: SubscriptionManager, route, i18n (sq Abonimet/en).
- The signed ledger `permitId` payload is intentionally kept — immutable
  hash-chained history; renaming it would break verification of past events.

Deferred (wiki notes): fee collection into the ledger/shift (a shift-attributed
payment), LPR/ANPR plate source, time-of-day access windows (overnight subscriber).

Also carries the device-footer UI surface (api DeviceStatus, router mount,
i18n devices) due to shared-file overlap with the preceding footer commit.

Verified end-to-end on a fresh DB and migration on a live-DB copy (sessions
preserved). Live DB migrated. Full monorepo builds clean.

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

wiki/concepts/shift.md

@@ -63,7 +63,9 @@ login ————————————————————————
 ## What End Shift does
 
 1. Determine the shift's payment set: the signed `payment` events ([[parking-session]],
-   [[append-only-event-chain]]) between this shift's start mark and now.
+   [[append-only-event-chain]]) between this shift's start mark and now. This includes a
+   **[[subscription]] fee** an operator collects during the shift (sold/renewed at the booth → a
+   signed `payment`, deferred build) — it folds into this set like any transient taking.
 2. Sum by **tender**: `cashTotal`, and `cardTotal` from the POS/terminal **if a POS is configured**
    (the card line is omitted when there's no terminal).
 3. Append a signed **`shift_z_report`** event (type already in `packages/shared`): `{ operator,