[tobias-tengler]

When a source response spans arena chunks that occupy adjacent ranges of the same byte array, Fusion still builds a linked sequence for the JSON reader. This allocates temporary sequence nodes and makes the reader process segmented input even though the bytes are contiguous.

This change recognizes the same backing array and exact adjacent offsets, then reads that range as one contiguous sequence. The original chunk table, packed data coordinates and document ownership stay intact. Gapped ranges and separate arrays use the existing linked sequence after the adjacency check.

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Known length, 128 B	main	838.737 ns	1.00	1192 B	1.00
Known length, 128 B	PR	825.232 ns	0.98	1192 B	1.00
Unknown length, 4 KiB	main	1027.061 ns	1.00	1282 B	1.00
Unknown length, 4 KiB	PR	967.155 ns	0.94	1137.5 B	0.89
Unknown length, 32 KiB	main	3407.502 ns	1.00	1426 B	1.00
Unknown length, 32 KiB	PR	3130.398 ns	0.92	1139 B	0.80

[github-actions]

Patch coverage

100.0% of changed lines covered (16/16)

File	Covered	Changed	Patch %
…/src/Fusion.Execution/Text/Json/SourceResultDocument.Parse.cs	16	16	100.0% 🟢

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Project coverage: 59.0% (311341/527669 lines)

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