feat(server): add OpenTelemetry tracing and metrics support

Adds comprehensive OpenTelemetry instrumentation for better observability:

Tracing:
- HTTP requests via @opentelemetry/instrumentation-http
- NestJS controllers via @opentelemetry/instrumentation-nestjs-core
- Redis operations via @opentelemetry/instrumentation-ioredis
- BullMQ job queues via bullmq-otel
- Database queries via Kysely log callback with accurate timing
- File operations (send, stream, read)
- Media processing (thumbnails, thumbhash, EXIF operations)
- Metadata extraction

Metrics:
- Database connection pool usage (used/idle connections)

The SDK is initialized in telemetry-preload.ts which is preloaded via
--require before the main app starts. This ensures http instrumentation
hooks are in place before any http module is imported.

Enable tracing by setting OTEL_EXPORTER_OTLP_ENDPOINT environment variable.

Also adds TraceContext to IBaseJob for future distributed trace propagation
across BullMQ job boundaries.

server/bin/start.sh

@@ -39,7 +39,7 @@ else
 fi
 
 if [ -f "${SERVER_HOME}/dist/main.js" ]; then
-  exec node "${SERVER_HOME}/dist/main.js" "$@"
+  exec node --require "${SERVER_HOME}/dist/telemetry-preload.js" "${SERVER_HOME}/dist/main.js" "$@"
 else
   echo "Error: ${SERVER_HOME}/dist/main.js not found"
   if [ "$IMMICH_ENV" = "development" ]; then