0.6.1 - Gap-triggered rescue

Adds one rescue trigger, measured across the same 100 recordings used to validate 0.6.0.

The change

• A recording whose largest contiguous uncovered stretch reaches 8 seconds now fires one rescue pass, alongside the existing low word-rate trigger. It cannot requeue or quarantine, and the 20 second threshold that feeds the quarantine path is untouched.
• The same measurement was already present but priced as a gate, where a false positive costs a whole transcript, so it sat at 20 seconds and caught 3 of 7 confirmed content losses. Priced as a trigger, where a false positive costs one extra decode, 8 seconds catches all 7. The detector was never missing. Nobody had re-priced it for a cheaper consequence.
• The longest run of words the unpublished pass holds and the published one lacks is now logged as a review marker. It needs no extra decoding, since both transcripts are already in memory wherever the rescue ran.

Measured on 102 recordings

• The rescue fires on 20, is selected on 11, and 7 of those measurably recover real content against the archive. Two are complete scripture readings restored to sermons that were missing them: Matthew 12:15-16 and Matthew 6:19-21, both going from partial to essentially complete.
• Cost is 13.8 percent more decode time, not the 24 percent predicted. The prediction priced a rescue as a second full decode; it is closer to two thirds of one, because it samples rather than beam-searches.
• Every one of the 11 selected rescues is strictly additive. The discarded pass held nothing the published one lacks, on all 11.
• No recording lost more than 5 percent against 0.6.0. No selected rescue lost content. The retention guard was exercised and refused a rescue that would have lost 1.25 percent. Alignment applied on every affected recording, with and without the rescue.

Known and recorded

• One recording fires the trigger and still publishes about 15 percent short. The trigger now sees it; the remedy does not fix it.
• On one recording the rescue recovers a 156 word reading from Exodus 24 but is discarded on a tie, because the selection rule cannot see that one pass holds a large contiguous passage the other lacks. Under investigation rather than changed blind, since that rescue is also several hundred words shorter overall and it is not yet established whether those words are content or repetition.
• The rescue samples without a seed, so recovery is an expectation across the corpus rather than a promise for any one sermon. Selection differed on 2 of 11 recordings between two runs of the same build.

The public API is unchanged.