fix(observe): re-enter record-less screen analysis outputs
Make processing_record the shared source of truth for analysis-output evidence by moving the bounded JSONL row-key detector there with audio and screen row-key constants, then route cluster through that helper.
An existing analysis output now blocks re-entry only when it carries evidence: analyzed rows or a processing record. Outputs with neither are indeterminate and re-enter until the record ledger can govern them; the record-less clause is describe/screen-only.
Decode-determined corrupt_input and empty verdicts terminalize regardless of provider availability, while runs that still have qualified frames to describe continue to defer when no brain is configured.