feat(m15): opt-in logging + per-diagnostic storage + Report bundles — 0.30.0

One `logging_enabled` toggle (default off) gates everything (D25):
- core/applog.py: rotating app.log (no-op unless enabled); setup() at GUI/CLI start.
- core/diagstore.py: each diagnostic stored in DATA_DIR/diagnostics/<id>/ (capture,
  result.json, report.txt, scoped gamelogs, ai/ records of exactly what was sent to
  the model + which model + the reply). make_report() zips a diagnostic (+ app.log)
  into DATA_DIR/reports/.
- diagnostic.finish()/analyze_crash() store when enabled; DiagnosticResult.dir.
- GUI: Settings → Logging toggle; "Report" button on the diagnostic dialog; AI
  interactions recorded into the diagnostic dir on "Explain with AI".
- CLI: `rigdoctor bundle` (report is taken by the M4 health report).
- Tests for store/record_ai/make_report + applog gating; docs (D25, M15, Phase 8).

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

docs/DECISIONS.md

@@ -264,9 +264,21 @@ root cause + suggested next steps). Adds M14 to the D14 set.
   as suggestions (consistent with D9 — it explains/recommends, applying fixes stays
   consent-gated). No new runtime dependency (HTTP via stdlib).
 
+### D25 — Logging & report bundles (M15) — *DECIDED 2026-05-22*
+Opt-in logging + shareable diagnostic reports.
+- **One combined `logging_enabled` toggle** (default off) controls both application logging
+  (rotating `app.log`) and per-diagnostic storage. Kept as a single switch for simplicity.
+- **Each diagnostic is stored in its own directory** (`DATA_DIR/diagnostics/<id>/`): capture
+  log, structured `result.json`, human-readable `report.txt`, a scoped game-log snapshot, and an
+  `ai/` folder recording each AI interaction (**exact data sent, provider+model, and the reply**).
+- **"Report"** zips one diagnostic directory (plus `app.log`) into `DATA_DIR/reports/` —
+  auto-saved there (no save dialog), shown with its path. Available only when logging is on
+  (nothing is stored otherwise). CLI: `rigdoctor bundle`.
+- Everything stays local; the report only leaves the machine if the user shares the zip.
+
 ## Open
 
-None currently — all tracked decisions (D1–D24) are resolved. New questions will be added
+None currently — all tracked decisions (D1–D25) are resolved. New questions will be added
 here as they arise. Remaining detail to flesh out during build: the tray's supporting-action
 set (D13), per-module apt package names, M12's tunnel/token specifics, and M13's
 update mechanism (APT repo vs. self-installed `.deb`).