Refresh documentation and policies and simplify releases

docs/roadmap/runtime-behavior.md

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+# Runtime Behavior Decisions
+
+**Last updated:** 2026-09-23
+
+The documentation migration identified these existing behaviors for separate
+product consideration. No behavior change is approved or implemented by this list.
+
+- Decide whether the `never` retention selection should delete successful-run
+  diagnostics; current behavior is documented in
+  [operations](../operations.md#retention-behavior).
+- Decide whether an explicit zero retry count should disable retries; current
+  adapter behavior is documented in [configuration](../config.md).
+- Decide whether missing or null input timestamps should be rejected; current
+  decoding is documented in the [input contract](../integrations/transcript-glossary-files.md).
+
+These decisions are independent of the completed documentation migration and
+release workflow.