feat(m15): collect session-scoped system logs (kernel + coredumps) — 0.31.0

core/syslogs.py gathers, scoped to the diagnostic window:
- kernel-log slice (journalctl -k): Xid, OOM, MCE, PCIe AER, thermal, hung tasks
- crashed-process records (coredumpctl): exe, signal, when
Stored as syslogs.txt in the diagnostic dir, included in the Report bundle, and
fed to the AI on "Explain" alongside the game logs. Best-effort (degrades if the
tools are missing/denied); treats journalctl's "-- No entries --" as empty.
Tests + docs (M15/SPEC).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to RigDoctor are recorded here. Format follows
 (`MAJOR.MINOR.PATCH`, pre-1.0). `__version__` and `pyproject.toml` must match the git
 release tag (so the auto-updater, D18, can compare versions).
 
+## [0.31.0] - 2026-05-22
+### Added
+- **Diagnostics now collect session-scoped system logs** (`core/syslogs.py`): a kernel-log
+  slice (`journalctl -k` — Xid, OOM-killer, MCE, PCIe AER, thermal, hung tasks) and
+  **crashed-process records** (`coredumpctl` — which executable, signal, and when). They're saved
+  to the diagnostic directory (`syslogs.txt`), included in the **Report** bundle, and fed to the
+  AI on "Explain" alongside the game logs. Best-effort — degrades quietly if the tools are
+  missing or access is denied; scoped to the session window so it doesn't drag in old noise.
+
 ## [0.30.0] - 2026-05-22
 ### Added
 - **Logging & report bundles (M15, D25)** — opt-in via one **Settings → Logging** toggle