Forward opaque metrics selectors to the API

[no-itsbackpack]

Summary

• accept opaque query pattern IDs in both metrics show and metrics queries
• stop prevalidating tablet workflow names against only the first workflow page
• add regression coverage that verifies selectors reach the metrics API unchanged

Test plan

• go test ./internal/cmd/metrics -count=1

[cursor]

Risk: low. Approved after Cursor Bugbot completed successfully with no findings that need human review; Cursor Security Agent was not running. No reviewers were assigned.

  

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