fix(3.6.8): JSON parse resilience + diagnostics for local model failures

- extract_findings: log when model output has no JSON (was silent drop)
- extract_findings: auto-fix trailing-comma JSON (common LLM mistake)
- pipeline: emit response tail when agent returns 0 parseable findings
- Helps diagnose why small/local models produce 0 findings on valid targets

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

RELEASE.md

@@ -17,6 +17,13 @@
 - **Single-model + vote_n=1 warning.** When only one model is configured and
   vote_n is 1, the pipeline emits a warning that validation is weaker (same model
   validates its own findings).
+- **JSON parse resilience for local models.** `extract_findings` now logs when a
+  model returns text but no parseable JSON (previously silent drop — 0 findings
+  with no diagnostic). Also auto-fixes trailing-comma JSON (`[...,]`) which small
+  models commonly produce.
+- **Visible diagnostics when agents return 0 findings.** Pipeline emits the
+  response tail so the operator can see what the model actually returned (helps
+  debug model quality issues with local/small models).
 
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