feat: explainable activity log — reasons, subscriber names, snapshot gaps

The live activity feed flagged anomalies with no explanation and showed
opaque session keys. Make events self-describing and clickable.

- Clickable feed rows → read-only event-detail modal: humanized fields,
  entry/exit snapshots, and signed-chain provenance collapsed behind an
  audit disclosure (operator sees the story, auditor expands for crypto).
- Localized reason codes (backend i18n): the signed ledger now carries a
  stable REASON_CODE + params (+ English fallback) instead of free-text
  English. The UI translates via reason.<code> catalogs in sq/en, so an
  Albanian operator reads Albanian — from the same immutable event. Adding
  a language is a catalog change, no re-signing. (@parking/shared
  REASON_CODES, reasonPayload; entry/exit/subscription flows emit codes.)
- Subscriber-name resolution: a SUBSESS-… occurrence now shows the
  subscription holder's name (fallback "Abonent"/"Subscriber"). Resolved
  read-time server-side (events API + WS push) as a non-signed
  subscriberLabel; cached with invalidation on subscription edit/delete.
- Failed-snapshot visibility: a camera that was attempted but unreachable
  now shows a "⚠ camera unreachable" tile instead of a silent gap. The
  snapshots API returns failures[] from telemetry, filtered so a recovered
  capture shows no stale warning.

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

apps/server/src/entry-flow.ts

@@ -10,7 +10,7 @@ import {
   type TicketData,
   type TicketHeader,
 } from "@parking/devices";
-import { DEFAULT_VEHICLE_CATEGORY } from "@parking/shared";
+import { DEFAULT_VEHICLE_CATEGORY, reasonPayload } from "@parking/shared";
 import type { FastifyBaseLogger } from "fastify";
 import type { DeviceInputEvent } from "./device-events.js";
 import { getOccupancy } from "./occupancy.js";
@@ -82,7 +82,11 @@ export class EntryFlow {
     if (occ.full) {
       await this.#log.append({
         type: "anomaly",
-        payload: { reason: `transient entry refused — lot full (${occ.count}/${occ.capacity})`, entryRefused: true, full: true },
+        payload: {
+          ...reasonPayload("entry.refused.full", { count: occ.count, capacity: occ.capacity ?? 0 }),
+          entryRefused: true,
+          full: true,
+        },
       });
       this.#logger.warn(`transient entry REFUSED: full (${occ.count}/${occ.capacity})`);
       return;
@@ -107,7 +111,7 @@ export class EntryFlow {
       await this.#log.append({
         type: "anomaly",
         identity: ticketId,
-        payload: { reason: `entry held — ticket not printed: ${reason}`, ticketPrinted: false },
+        payload: { ...reasonPayload("entry.held.noTicket", { detail: reason }), ticketPrinted: false },
       });
       this.#logger.warn(`entry HELD: ${reason} (barrier NOT opened)`);
       return;