[4] [TASK] [Backend] [API] Implement POST /api/v1/telemetry/batch Endpoint

[R4R35]

Description

Implement an additional REST endpoint capable of receiving an array of telemetry data points to support offline caching and background synchronization from the mobile app.

Scope

• Update TelemetryController to expose POST /api/v1/telemetry/batch.
• Accept a List<TelemetryPingDTO> as the request body.
• Update the async worker to handle bulk inserts (saving the entire list to MongoDB at once).

Done When

• A POST request containing a JSON array of telemetry pings returns 202 Accepted.
• All items in the array are successfully stored in the database collection.