Add v1.3.0-beta.2 release notes

Author: masarray

docs/RELEASE_NOTES_v1.3.0-beta.2.md

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+# Process Bus Insight v1.3.0-beta.2
+
+This stabilization beta focuses on repeatable runtime evidence before the larger v1.4 runtime decomposition. It does not add control or publishing behavior and preserves the receive-only engineering boundary.
+
+## Highlights
+
+- Deterministic eight-stream SV isolation regression coverage
+- Exact 2/4/8-cycle scope-window regression coverage
+- Explicit 65536 sample-counter rollover coverage in addition to the existing rate-rollover tests
+- Duplicate and forward-gap evidence checks while preserving the last coherent scope window
+- Waveform and RMS coherence checks from the same selected-stream sample window
+- Concurrent frame-observation and snapshot-read stress coverage
+- Repeated runtime-stability GitHub Actions gate with downloadable TRX evidence
+- Standardized field-evidence record for live capture and replay validation
+
+## Validation intent
+
+The automated stability suite exercises the same `ObserveFrame` and `GetAnalyzerSnapshot` surface used by the live analyzer. It uses deterministic synthetic IEC 61850 SV frames and does not require Npcap, customer captures, or proprietary SCL files.
+
+For a release decision, automated evidence must be combined with a maintained Windows/Npcap smoke test and a documented 30–60 minute soak session using sanitized field or replay sources.
+
+## Important limitations
+
+- This remains a public beta, not a certified protection or timing instrument.
+- Windows/Npcap packet timestamps remain screening evidence unless the capture path is independently validated.
+- The repeated automated stability gate is deterministic stress evidence, not a replacement for a real-duration field soak test.
+- Multi-vendor SCL semantic coverage still requires broader maintained evidence.
+- Npcap must be installed separately for live capture.