feat: add DELETE /collection/:id/resources endpoint

[Husainbw786]

What changed

Added a new DELETE endpoint for deleting resources from a collection by owner ID.

New endpoint: DELETE /collection/:id/resources?ownerId=<ownerId>

Changes made:

1. Added deleteResourcesByCollectionAndOwner controller function in rag.controller.js
2. Added deleteResourcesByCollectionQuerySchema validation schema in rag.validation.js
3. Added the DELETE route in rag.routes.js

Why

To support deleting resources from a collection based on the collection ID and owner ID. This follows the existing pattern used for other RAG endpoints.

Notes

• Uses the existing Hippocampus API endpoint: DELETE /collection/:collectionId/resources?ownerId=<ownerId>
• Protected with middleware and checkAgentAccessMiddleware consistent with other resource management endpoints
• ownerId is required as a query parameter

[windsurf-bot]

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