Fix UseSingleOrDefault ignoring explicit GraphQL field types

[michaelstaib]

• fix UseSingleOrDefault / UseFirstOrDefault type rewriting to preserve explicitly configured field GraphQL types
• only rewrite field type when the original field type is a list shape inferred from the resolver result
• add a regression test proving .Type<ObjectType<SingleOrDefaultActiveUser>>() is respected with UseSingleOrDefault

Fixes #5648

[github-actions]

Fusion Gateway Performance Results

Simple Composite Query

	Req/s	Err%
Constant 2 (50 VUs)	3289.79	0.00%
Ramping 2 (0-500-0 VUs)	3867.20	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	1.11ms	12.17ms	14.93ms	24.47ms	34.19ms	260.01ms
Ramping 2	1.16ms	50.95ms	56.66ms	99.21ms	144.20ms	318.18ms

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Deep Recursion Query

	Req/s	Err%
Constant 2 (50 VUs)	772.33	0.00%
Ramping 2 (0-500-0 VUs)	909.59	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	11.64ms	55.58ms	62.76ms	80.60ms	100.69ms	606.36ms
Ramping 2	3.06ms	205.13ms	226.16ms	464.20ms	536.83ms	937.03ms

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Variable Batching Throughput

	Req/s	Err%
Constant 2 (50 VUs)	5264.52	0.00%
Ramping 2 (0-500-0 VUs)	5127.53	0.00%

Response Times

	Min	Med	Avg	P90	P95	Max
Constant 2	0.18ms	8.85ms	9.38ms	15.71ms	18.80ms	53.19ms
Ramping 2	0.20ms	40.82ms	44.80ms	81.94ms	109.06ms	219.33ms

---

Runner 2 = benchmarking-2

Run 22419160302 • Commit 15081b1 • Wed, 25 Feb 2026 23:22:59 GMT