Previously the CSLOGGER_* console overrides and the verbose (silly) file level were gated behind isDev, so a packaged build could not raise its log level for troubleshooting. Replace the isDev gates in both the main and renderer LoggerService with isDev || DIAGNOSTICS_ENABLED, so setting CS_DIAGNOSTICS makes the logger behave exactly as in dev: verbose file level, console output, and the CSLOGGER_* filters all turn on together. Idempotent in dev.
Reuses the existing DIAGNOSTICS_ENABLED flag as the single source of truth; the renderer reads CS_DIAGNOSTICS via the preload-exposed process.env. Document the behavior in the diagnostics and logging guides.
Promote the temporary boot profiler into a permanent, opt-in diagnostics facility gated by CS_DIAGNOSTICS (off by default, zero overhead when unset). Move it to src/main/core/diagnostics.ts so the db and lifecycle layers no longer cross-import a lifecycle-internal file.
Probes, all gated by the same flag: per-service init timing, phase service spans, event-loop lag, and a whenReady V8 CPU profile (carried over); slow DB queries, now covering interactive-transaction interiors and batches (not just client.execute); slow IPC handlers (BaseService.ipcHandle); window construction + ready-to-show latency (WindowManager); and slow DataApi requests (ApiServer).
DataApi request duration is consolidated to a single monotonic performance.now() measurement in handleRequest, computed only when enabled; the redundant Date.now() duration in MiddlewareEngine is removed and metadata.duration is now optional.
Packaged-build safe: the CPU profile is written to the app logs directory (not process.cwd()) and a failed write can never break boot. Thresholds live in SLOW_THRESHOLD_MS; usage in docs/guides/diagnostics.md.
Also demote per-service stop/destroy logs to debug to quiet shutdown output.
