Fix Clair3 model download staging when explicit override bypasses aut…

[YannVRB]

…o-detection

PREPARE_REFERENCE_FILES computed the WGET/UNTAR staging directory name (meta_new.id) independently from the actual download URL (model): the URL correctly fell back to the samplesheet's explicit clair3_model override when basecall_model_meta didn't match clair3_modelMap, but the staging id did not -- it was only ever clair3_modelMap.get(basecall_model_meta), which resolves to null on any unmapped model. UNTAR then failed with "mkdir: missing operand" because its output directory name came out empty, even though the model itself downloaded successfully under the correct override.

This isn't specific to any one basecall model -- it triggers for any sample whose auto-detected basecall_model_meta isn't in clair3_modelMap (currently only dna_r10.4.1_e8.2_*_sup@v4.x/v5.x and hifi_revio are mapped), whether that's because the model genuinely isn't supported yet, or because BAM header metadata is missing/malformed. H

Fix: derive meta_new.id from the same resolved model value used for the download URL, so an explicit clair3_model override always works regardless of whether the auto-detected model has a modelMap entry.

Claude-Session: https://claude.ai/code/session_01DhE7yZ2qRjaG86P7JgZbA4

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