[Repo Assist] feat: add Group 1 AsyncSeq design-parity functions (replicateInfinite, firstOrDefault, lastOrDefault, splitAt, zipWith, chunkBy, [Content truncated due to length]

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🤖 This PR was created by Repo Assist, an automated AI assistant, at the request of @dsyme.

Summary

This PR implements the "Group 1" pure sequence operations identified in the AsyncSeq/TaskSeq design-parity gap analysis on issue #345, excluding distinctUntilChangedWith/distinctUntilChangedWithAsync (already in PR #346).

New functions added

Function	Signature	Description
replicateInfinite	'T -> TaskSeq<'T>	Infinite sequence repeating a constant value
replicateInfiniteAsync	(unit -> #Task<'T>) -> TaskSeq<'T>	Infinite sequence from an async thunk
replicateUntilNoneAsync	(unit -> #Task<'T option>) -> TaskSeq<'T>	Sequence from async thunk, stops on None
firstOrDefault	'T -> ('T -> bool) -> TaskSeq<'T> -> Task<'T>	First matching element or default
lastOrDefault	'T -> ('T -> bool) -> TaskSeq<'T> -> Task<'T>	Last matching element or default
splitAt	int -> TaskSeq<'T> -> Task<'T[] * TaskSeq<'T>>	Split prefix of N elements from remainder
zipWith	('T -> 'U -> 'V) -> TaskSeq<'T> -> TaskSeq<'U> -> TaskSeq<'V>	Zip two sequences with a mapping function
zipWithAsync	('T -> 'U -> #Task<'V>) -> TaskSeq<'T> -> TaskSeq<'U> -> TaskSeq<'V>	Async variant of zipWith
zipWith3	('T -> 'U -> 'V -> 'W) -> TaskSeq<'T> -> TaskSeq<'U> -> TaskSeq<'V> -> TaskSeq<'W>	Zip three sequences with a mapping function
zipWithAsync3	('T -> 'U -> 'V -> #Task<'W>) -> ...	Async variant of zipWith3
chunkBy	('T -> 'Key) -> TaskSeq<'T> -> TaskSeq<'T[]>	Chunk consecutive elements with equal keys
chunkByAsync	('T -> #Task<'Key>) -> TaskSeq<'T> -> TaskSeq<'T[]>	Async variant of chunkBy
threadState	('State -> 'T -> 'U * 'State) -> 'State -> TaskSeq<'T> -> TaskSeq<'U>	Stateful map threading state through sequence
threadStateAsync	('State -> 'T -> #Task<'U * 'State>) -> 'State -> TaskSeq<'T> -> TaskSeq<'U>	Async variant of threadState

Test coverage

326 new tests across 6 new test files:

Test file	Tests	Coverage
TaskSeq.ReplicateInfinite.Tests.fs	~55	Empty/null guards, infinite generation, async thunk, replicateUntilNoneAsync
TaskSeq.FirstLastDefault.Tests.fs	~50	Null guards, not-found default, predicate matching, sync/async
TaskSeq.SplitAt.Tests.fs	~55	Null guards, split at 0/N/end/beyond, remainder laziness
TaskSeq.ZipWith.Tests.fs	~60	Null guards, empty sequences, zipping, async variants, zipWith3
TaskSeq.ChunkBy.Tests.fs	~55	Null guards, single chunk, multi-chunk, consecutive grouping
TaskSeq.ThreadState.Tests.fs	~51	Null guards, state threading, accumulation, async variant

Changes

File	Change
TaskSeqInternal.fs	+~250 lines: all 14 new internal implementations
TaskSeq.fsi	+~100 lines: XML-documented public signatures
TaskSeq.fs	+~60 lines: dispatch wrappers
TaskSeq.*.Tests.fs	6 new test files, ~1,100 lines
FSharp.Control.TaskSeq.Test.fsproj	6 new (Compile) entries
release-notes.txt	7 new bullets under 1.0.0

Test Status

✅ Build: dotnet build src/FSharp.Control.TaskSeq.sln -c Release — succeeded, 0 warnings, 0 errors
✅ Format: dotnet fantomas . --check — all files correctly formatted
✅ Tests: dotnet test ... -c Release — 4,942 passed, 2 skipped (infrastructure), 0 failed

Notes

• splitAt follows the same disposal pattern as tryTail — the returned TaskSeq<'T> remainder captures the enumerator and works correctly for in-memory/replayable sequences.
• replicateInfiniteAsync takes a unit -> #Task<'T> thunk (not a bare Task<'T>) since Tasks are single-use hot-started computations.
• chunkBy yields consecutive-equal-key chunks (like Seq.chunkBy in AsyncSeq), not groupBy.
• This PR may have merge conflicts with PR [Repo Assist] feat: add TaskSeq.distinctUntilChangedWith and distinctUntilChangedWithAsync #346 on release-notes.txt — coordinate merging order.

Closes #345 (partially — Group 1 functions only; Group 2/3 remain for future work).

Generated by Repo Assist for issue #345 · ◷

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