[BE-27] Implement BullMQ job queue for async asset processing in opsce module

[yusuftomilola]

Problem

Operations like PDF generation, Stellar contract calls, and bulk exports are slow synchronous operations that block the request-response cycle. bull and @nestjs/bull are available but not configured.

Proposed Solution

Create backend/src/opsce/queue/ with a QueueModule, an AssetProcessor for asset-related jobs, and a queue producer service. Use Redis as the BullMQ backend.

Acceptance Criteria

• QueueModule configured with Redis using REDIS_HOST and REDIS_PORT env variables
• asset-processor handles: generate-pdf and stellar-tokenize job types
• Jobs have 3 retry attempts with exponential backoff on failure
• GET /api/assets/:id/report enqueues a generate-pdf job and returns a jobId immediately
• GET /api/queue/jobs/:jobId returns job status (waiting/active/completed/failed)
• Failed jobs log structured error details including jobId, type, and error message

[GreatShinro]

@GreatShinro has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi, can I work on this please?

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[Divineifed1]

@Divineifed1 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hello Maintainer, can I work on this task

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[drips-wave]

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