Ships a new public J2KDICOMHelpers library that bridges DICOM Transfer
Syntax UIDs to J2KEncodingConfiguration. Closes a long-standing product-
layer gap: library consumers using their own DICOM parser (DICOMKit,
pydicom-via-XPC, etc.) get a Transfer Syntax UID + Pixel Data bytes, and
previously had to hand-roll the UID-to-config mapping.

Per ADR-004, J2KSwift core libraries don't depend on any DICOM library.
The CLI ships a DICOMSupport.swift for .dcm file loading, but the
DICOMTransferSyntax / DICOMTransferSyntaxInfo types there are CLI-private
— not surfaced to library consumers. v10.17.0 lifts the UID-bridge layer
into a new public SwiftPM library.

Public surface:

  * J2KDICOMTransferSyntax — CaseIterable enum over all 7 DICOM Part 5
    Annex A JPEG 2000 / HTJ2K UIDs (j2kLossless 90, j2kLossy 91,
    j2kPart2MulticompLossless 92, j2kPart2Multicomp 93, htj2kLossless 201,
    htj2kLossyConstant 202, htj2kLossy 203). init?(uid:) / var uid round-trip
    (whitespace + trailing-NUL tolerant per PS3.5 §6.2). isLossless /
    isHTJ2K / isPart2 classification flags.

  * J2KDICOMTransferSyntax.encodingConfiguration(bitDepth:psnrTarget:) —
    returns matching J2KEncodingConfiguration with htj2kBlockFormat:
    .conformant for DICOM interop.

  * J2KDICOMCodestreamDetector.detect(_:) — sniffs SOC + (optional) CAP
    markers in the first ~256 bytes to classify raw codestreams as
    .j2kLossless (Part 1, no CAP) or .htj2kLossless (Part 15, CAP present).
    Returns nil for non-J2K bytes (JPEG SOI, PNG sig, random bytes all
    correctly reject).

  * J2KDICOMPhotometricInterpretation — enum mirror of the 7 DICOM
    PhotometricInterpretation values relevant to J2K. Bidirectional
    J2KColorSpace mapping (greyscale ↔ MONOCHROME2, sRGB ↔ RGB,
    yCbCr ↔ YBR_FULL; hdr/hdrLinear/iccProfile/unknown return nil
    in reverse).

ADR-004 compliant: no DICOM library dependency anywhere in J2KSwift —
the new product depends only on J2KCore + J2KCodec. Consumers not
importing J2KDICOMHelpers are completely unaffected.

Phase 1 deliberately ships the smallest viable shape — UID-and-config
bridge only. Phase 2 (likely v10.18+) would extract more of
J2KCLI/DICOMSupport.swift's file-parsing logic or ship a DICOMKit
adapter as a sibling opt-in product.

AsyncSequence progress streams (originally Phase 3 of the v10.17.0
plan) deferred to a dedicated MINOR — the AsyncStream-vs-actor-stored-
callback lifecycle has subtle correctness questions that warrant a
focused ship rather than being squeezed in.

Validation:
- V10_29_TransferSyntaxRoundTripTests 9/9 PASS
- V10_29_EncodingConfigurationParityTests 5/5 PASS (incl. bit-exact
  lossless round-trip via helper-built configs)
- V10_29_CodestreamDetectionTests 6/6 PASS
- V10_29_PhotometricInterpretationTests 6/6 PASS
- V10_29 total: 26/26 PASS release mode
- swift test --filter JP3D regression 528/528 PASS (1 pre-existing skip)
- Mandatory commit gate (release mode) 7/7 PASS

MINOR per RELEASING.md — entirely additive: new product, zero touch to
existing libraries, codestream bytes byte-identical to v10.16.0, no
DICOM library dependency added anywhere. Also bumps getVersion()
constant 10.16.0 → 10.17.0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>