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/routes/snapshots.ts

@@ -1,5 +1,5 @@
 import type { FastifyInstance } from "fastify";
-import { desc, eq, snapshots, type Db } from "@parking/db";
+import { and, desc, eq, deviceEvents, snapshots, type Db } from "@parking/db";
 import { requirePermission } from "../auth.js";
 
 // Read access to captured entry/exit snapshots (the BLOB-in-DB image store, see
@@ -12,11 +12,15 @@ export async function snapshotRoutes(app: FastifyInstance, db: Db): Promise<void
   const guard = requirePermission("session:read");
 
   // Snapshot metadata for one session/credential identity (NOT the bytes), newest
-  // first — lets the UI show "entry/exit image" links beside an event.
+  // first — lets the UI show "entry/exit image" links beside an event. We also return
+  // FAILED capture attempts (from snapshot telemetry) so the operator can tell a
+  // camera that was offline from a direction that simply has no camera — otherwise a
+  // missing shot is a silent gap. See snapshot.ts (recordFailure).
   app.get<{ Params: { identity: string } }>(
     "/api/snapshots/by-identity/:identity",
     { preHandler: guard },
     async (req) => {
+      const identity = req.params.identity;
       const rows = db
         .select({
           id: snapshots.id,
@@ -27,10 +31,44 @@ export async function snapshotRoutes(app: FastifyInstance, db: Db): Promise<void
           capturedAt: snapshots.capturedAt,
         })
         .from(snapshots)
-        .where(eq(snapshots.identity, req.params.identity))
+        .where(eq(snapshots.identity, identity))
         .orderBy(desc(snapshots.capturedAt))
         .all();
-      return { snapshots: rows };
+
+      // Failed attempts: kind="snapshot" telemetry whose detail.identity matches and
+      // detail.ok === false. There may be both a failure and (on a retry) a success
+      // for the same direction; we keep only failures with NO successful shot in the
+      // same direction, so a recovered capture doesn't show a stale warning.
+      const haveDir = new Set<string | null>(rows.map((r) => r.direction));
+      const telemetry = db
+        .select({ detail: deviceEvents.detail, deviceId: deviceEvents.deviceId, occurredAt: deviceEvents.occurredAt })
+        .from(deviceEvents)
+        .where(and(eq(deviceEvents.category, "camera"), eq(deviceEvents.kind, "snapshot")))
+        .orderBy(desc(deviceEvents.occurredAt))
+        .all();
+      const failures: {
+        direction: "entry" | "exit" | null;
+        deviceId: string;
+        error: string;
+        occurredAt: string;
+      }[] = [];
+      const seenFailDir = new Set<string>();
+      for (const row of telemetry) {
+        const d = (row.detail ?? {}) as { identity?: string; ok?: boolean; error?: string; direction?: string };
+        if (d.identity !== identity || d.ok !== false) continue;
+        const dir = d.direction === "entry" || d.direction === "exit" ? d.direction : null;
+        const dirKey = dir ?? "both";
+        if (haveDir.has(dir) || seenFailDir.has(dirKey)) continue; // a success exists, or already shown
+        seenFailDir.add(dirKey);
+        failures.push({
+          direction: dir,
+          deviceId: row.deviceId ?? "",
+          error: d.error ?? "capture failed",
+          occurredAt: row.occurredAt ?? "",
+        });
+      }
+
+      return { snapshots: rows, failures };
     },
   );