fix(sfcompute): build instance name from RefID and environment ID

[jainvishesh11]

Problem

Environment creation on SFCompute v2 fails with:

status 400: {"error":{"type":"invalid_request_error","message":"an instance with this
name already exists","details":[{"field":"name","code":"duplicate"}]}}

Root Cause

SFCompute treats the instance name as a unique key per workspace, and every Brev environment on a cloud credential shares one workspace. CreateInstance sent only the sanitized user-supplied environment name, while the globally unique RefID went to tags only, which SFCompute ignores for uniqueness.

Fix

Compose the name from Brev IDs instead of the user's supplied environment name:

func makeSFCName(refID string, tags v1.Tags) string {
    return sanitizeSFCName(refID + "-" + tags["dev-plane-x-environmentId"])
}

Giving e.g. inst-2toqsvHXfalevkjPXY2QNJZL9HF-p82qfn5qs. The Instance ID is a primary key so the name is unique per instance and the environment ID is also included for searchability.

Files changed

v1/providers/sfcomputev2/instance.go : added makeSFCName; CreateInstance uses it instead of sanitizeSFCName(attrs.Name)
v1/providers/sfcomputev2/instance_test.go : added tests for determinism (retry safety) and uniqueness across instances

Related Ticket

BREV-12012