feat(utility): add printf-style frame pattern support (%04d)

[throb]

Summary

• Add printf-style frame sequence pattern support (%04d, %06d, etc.) to parse_cli_posix_path(), complementing existing hash (####) and fmt ({:04d}) patterns
• Handle Nuke-style space-separated frame ranges (file.%04d.exr 1000-1080) in addition to equals syntax (file.%04d.exr=1000-1080)
• Defensive conversion in frame_groups_from_sequence_spec() for paths that bypass the main parser

Motivation

Printf-style frame patterns are the standard format used by ShotGrid/Flow Production Tracking, Nuke, Houdini, and most VFX pipeline tools. Without this, integrating xSTUDIO with production tracking systems requires workarounds like directory scanning instead of direct path loading.

Changes

File	Change
src/utility/src/helpers.cpp	Add xstudio_printf and xstudio_prefix_printf regex patterns, printf_to_fmt converter, space-separated range normalization
src/utility/src/frame_list.cpp	Add %0Nd → {:0Nd} conversion in frame_groups_from_sequence_spec()

Supported inputs (new)

file.%04d.exr=1000-1080       printf + equals range
file.%04d.exr 1000-1080       printf + space range (Nuke style)
file.1234.%04d.exr            printf with prefix frame number
/full/path/shot.%06d.exr      variable padding width

All existing patterns (####, {:04d}, =range) continue to work unchanged.

Test plan

• parse_posix_path("test.%04d.exr=1000-1080") → URI test.{:04d}.exr, FrameList 1000-1080
• parse_posix_path("test.%04d.exr 1000-1080") → same result (space-separated)
• parse_posix_path("test.####.exr 1000-1080") → hash + space also works
• parse_posix_path("test.{:04d}.exr 1000-1080") → fmt + space also works
• parse_posix_path("shot.%06d.exr 100-200") → variable padding width
• Existing hash and fmt patterns unchanged
• Tested with real ShotGrid paths loading EXR sequences in xSTUDIO

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