Allow preselecting a workflow before uploading files

[martsokha]

Summary

When uploading files, let the user preselect the workflow (pipeline) that should process them, before the upload starts.

Problem

Today the upload flow (UploadFilesDialog.vue on /w/{slug}/files) has no way to choose which pipeline runs against the uploaded files — there's no pipeline/workflow field in the dialog. Users can't direct their documents to a specific detection/redaction pipeline at upload time; the association (if any) happens elsewhere or by default.

Proposed

• Add a workflow (pipeline) selector to the upload dialog, populated from the workspace's pipelines (usePipelines).
• The chosen pipeline is applied to the files being uploaded (attached to the upload request / triggering that pipeline's run).
• Sensible default when the workspace has one pipeline; a clear empty state / hint when it has none (with a link to create one).

Notes / open questions

• SDK support: confirm the upload/file-create endpoint accepts a pipeline reference (e.g. a pipelineSlug on the upload or a follow-up trigger). If not, this needs an API/SDK change first.
• UX placement: a select at the top of UploadFilesDialog vs. a step before file selection.
• Multi-file: one pipeline for the whole batch (simplest) vs. per-file (probably out of scope for v1).
• Relates to the workflow-creation work in progress (feat/workflow-create).

Affected areas

• packages/console/app/components/pages/files/UploadFilesDialog.vue
• packages/console/app/composables/usePipelines.ts (list pipelines for the selector)
• Possibly the file-upload composable / SDK call, depending on how the pipeline is attached