feat(admin): app-log preview surfaces last 1h of structured events with filter + JSON inspector

Wires the in-memory ring buffer (`src/lib/logging/in-memory-buffer.ts`)
into `transports.emitEvent()` so every wide event that survives the
sampler also lands in a 500-entry per-process buffer. Adds the
`app-logs` admin section slug, the renderer case, and the route entry
exports needed for the new section component to mount.

The buffer is volatile and per-process — a worker-only event won't
show up in the web buffer, and a restart drops everything. The section
header copy spells that out so admins know to keep Loki configured for
durable diagnostics. Egress through `/api/admin/app-logs` runs every
event through `redactSecrets()` so a stray Bearer / hlk_ / sk- token
in an `error.message` never leaks to the admin UI; storage stays raw
to keep the diagnostic value when shipped to Loki.

The companion buffer + transports tests live under
`src/lib/logging/__tests__/in-memory-buffer.test.ts` and
`transports-buffer.test.ts` (committed separately as part of the
buffer scaffolding). The route-level tests in
`src/app/api/admin/app-logs/__tests__/route.test.ts` cover newest-
first ordering, traceId / level / action filters, the `limit` cap,
secret redaction on egress, and the Zod-rejected invalid `level` case.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/admin/section-slugs.ts

@@ -19,6 +19,7 @@ export const ADMIN_SECTION_SLUGS = [
   "users",
   "api-tokens",
   "login-overview",
+  "app-logs",
   "backups",
   "danger-zone",
 ] as const;