Clear Dry Run Filings

Delete undecided dry-run filing runs so a backfill can re-propose.

The backfill skips any source that already has a run, so a first pass with bad matches otherwise blocks a retry after tuning. This clears those proposals.

Deliberately narrow — only rows that are all of: dry-run, transcript filing, and still awaiting a decision ('proposed' / 'needs_review' / 'screened_out' / 'already_filed', or a failed run that never reached one). A run a human approved or rejected, and any run that executed a Drive write, is kept: re-proposing those would discard a human decision or duplicate a file. 'already_filed' is the automation's own verdict rather than a human's, and the re-run repeats the check, so it is clearable.