[tobias-tengler]

Fusion reserves a 13.6-million-entry reference table for its shared path-segment pool, allocating about 104 MiB even when only the initial 4,096 slots are needed.

This change allocates reference pages on demand, reducing initial allocation to about 58 KiB while preserving the batching and local reuse from #10548. Trim releases segment arrays and keeps the reference pages for reuse. After the tested 131,072-array peak, about 1 MiB of reference pages remains reserved.

Method	Version	Mean	Ratio
Warm reuse, 1,024 arrays, 1 worker	main	13.346 µs	1.00
Warm reuse, 1,024 arrays, 1 worker	PR	11.771 µs	0.88
Warm reuse, 1,024 arrays, 16 workers	main	13.969 µs	1.00
Warm reuse, 1,024 arrays, 16 workers	PR	10.550 µs	0.76
Grow, return and trim, 131,072 arrays, 16 workers	main	17.852 ms	1.00
Grow, return and trim, 131,072 arrays, 16 workers	PR	16.991 ms	0.95

[github-actions]

Patch coverage

97.3% of changed lines covered (72/74)

File	Covered	Changed	Patch %
…/Fusion/src/Fusion.Execution/Text/Json/PathSegmentPool.cs	72	74	97.3% 🟡

Uncovered changed lines (JSON)

{
  "sha": "4f395554c1e967e6b21885dfdfc4b5361195bdf8",
  "files": [
    { "path": "src/HotChocolate/Fusion/src/Fusion.Execution/Text/Json/PathSegmentPool.cs", "ranges": [[352, 352], [407, 407]] }
  ]
}

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Project coverage: 59.0% (311476/527757 lines)

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