Add uv process directive for Python package management

[evanroyrees]

Summary

Add a new uv process directive for managing Python dependencies via the uv package manager, following the existing conda and spack directive patterns.

Supports inline packages and requirements files:

process FOO {
    uv 'numpy pandas'
}

process BAR {
    uv "${moduleDir}/requirements.txt"
}

Changes

• UvConfig / UvCache — config scope and environment creation/caching
• Process directive registration, task execution integration (TaskBean, TaskRun, BashWrapperBuilder)
• Task hashing, lineage tracking, job array support
• CLI options (-with-uv / -without-uv), config builder, launcher arg normalization
• Environment variables (NXF_UV_ENABLED, NXF_UV_CACHEDIR)
• Documentation (process directive, config scope, env vars, docs/uv.md)
• Tests for all new and modified components

Signed-off-by: Evan Rees evanroyrees@gmail.com

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[bentsherman]

Thanks for the contribution, but I think we're going to hold off on adding new directives for each Python package manager. Instead we're looking into a generic package directive with multiple providers: #6342