perf(parquet/pqarrow): write binary values from Arrow offsets

[fallintoplace]

Summary

• Writes Binary, String, LargeBinary, and LargeString values from Arrow buffers and offsets.
• Removes the full []parquet.ByteArray allocation from non-dictionary writes.
• Keeps nullable writes, page statistics, bloom filters, page limits, and dictionary fallback behavior.
• Adds coverage for 32-bit and 64-bit offsets, nulls, slices, small batches, and all byte-array encodings.

Benchmark

64K String rows, uncompressed, dictionary disabled, Apple M1 Pro. Median of 3 runs with 3 seconds per run.

stats	before	after	heap/op
false	1.798 ms	1.260 ms	10.62 MB -> 9.04 MB
true	2.343 ms	1.861 ms	10.62 MB -> 9.06 MB

Benchmark command: go test ./parquet/pqarrow -run '^$' -bench '^BenchmarkWriteArrowBinaryOffsets$' -benchmem -benchtime=3s -count=3

Tests

• go test ./parquet/...
• go vet ./parquet/internal/encoding ./parquet/metadata ./parquet/file ./parquet/pqarrow

[zeroshade]

Just needs to fix the linting issue