Firebase maintenance: retire legacy fields in `results` and clarify the usage

[rugeli]

Use Case

We track client jobs and result lifecycle in the job_status collection. Some fields in the results collection were introduced early on and now overlap in purpose or are no longer actively used
After addressing #441, we should only receive local run results in this collection, and each document should have a human readable name

Proposed Solution

• retire unused fields in results (e.g. batch_job_id)
• clarify that results is intended for backend/internal use only (e.g. result window tab pop-up )
• add dedup_hash to each result to support reuse and deduplication