fix(pipeline): resume with --run flag fails to resolve artifact paths from prior run

[nextlevelshit]

Bug

When resuming a pipeline with --run <run-id> --from-step <step>, the resume manager correctly marks prior steps as completed (0.0s, 0 tokens) but fails to resolve artifact paths — it looks for artifacts in the default workspace path (speckit-flow-test/specify/) instead of the actual prior run's worktree (speckit-flow-20260306-084028-bd46/__wt_speckit-flow-20260306-084028-bd46/).

Steps to Reproduce

1. Run a pipeline that fails partway: wave run speckit-flow -- "..."
2. Pipeline completes steps 1-4 (specify, clarify, plan, tasks) then fails on step 5 (checklist)
3. Attempt resume: wave run speckit-flow --run speckit-flow-20260306-084028-bd46 --from-step checklist
4. Resume correctly skips completed steps but fails with:

failed to inject artifacts: failed to read required artifact 'spec-status': 
open .wave/workspaces/speckit-flow-test/specify/.wave/output/specify-status.json: no such file or directory

Expected

Artifact injection should resolve paths from the prior run's workspace (speckit-flow-20260306-084028-bd46), not the default workspace.

Actual

loadResumeState in internal/pipeline/resume.go loads step completion status but artifact paths map to the wrong workspace location.

Relevant Code

• internal/pipeline/resume.go:196 — loadResumeState()
• internal/pipeline/resume.go:301 — createResumeSubpipeline()
• Artifact injection logic needs to use WorkspacePaths from the prior run's state

Trace

[10:28:40] ✓ specify completed (0.0s, 0 tokens)
[10:28:40] ✓ clarify completed (0.0s, 0 tokens)
[10:28:40] ✓ plan completed (0.0s, 0 tokens)
[10:28:40] ✓ tasks completed (0.0s, 0 tokens)
[10:28:41] → checklist (implementer)
pipeline execution failed: ❌ Phase 'checklist' failed: failed to inject artifacts: 
  failed to read required artifact 'spec-status': 
  open .wave/workspaces/speckit-flow-test/specify/.wave/output/specify-status.json: no such file or directory

Part of TUI epic #251.

[nextlevelshit]

Fixed in 2519660. The --run flag value is now threaded through ResumeWithValidation → ResumeFromStep → loadResumeState using variadic ...string parameters for backward compatibility. When a prior run ID is specified, the resolver checks for the exact run directory first before falling back to the glob scan.

5 new test cases in TestLoadResumeState_WithPriorRunID.