GOG Galaxy "offline": it is GOG's own maintenance outage, not the LAN

www.gog.com serves GOG's maintenance page (503, "Galaxy Launcher will also be down");
auth/api/remote-config.gog.com return 500 "Fastly error: unknown domain". Proven
global by hitting it from a second egress (same 503); local DNS, TLS and clock are
clean, so there is nothing to fix on this machine.

Records the diagnosis recipe (where Galaxy 2.0 logs actually live, the log line
that decides the offline badge, and how to separate a GOG outage from a LAN
outage) in MyMistakes.md, and the operational note in HANDOFF.md.

No code touched - no build/test gate applies to this docs-only change.

HANDOFF.md

@@ -100,6 +100,13 @@ Zombie entities deleted from the registry: `script.leak_strobe`, `script.doorbel
   intended target before starting — do not assume.
 
 ## Open (operational)
+- **GOG Galaxy launcher shows "offline" (2026-10-21) — GOG-side outage, NOT the LAN.** GOG put
+  `www.gog.com` behind a maintenance page (503) and their Fastly services for `auth.gog.com` /
+  `api.gog.com` / `remote-config.gog.com` return `500 "Fastly error: unknown domain"`; the page itself
+  says *"Galaxy Launcher will also be down."* `status.gog.com` is NXDOMAIN globally. Proven global by
+  hitting it from a second egress (same 503), and the local DNS/TLS/clock are all fine. **Nothing to fix
+  locally** — wait for GOG. Diagnosis recipe: `MyMistakes.md` → 2026-10-21 GOG Galaxy "offline".
+  Galaxy 2.0 logs live in `C:\ProgramData\GOG.com\Galaxy\logs\` (NOT `%LOCALAPPDATA%`).
 - **verify.sh's known-failure whitelist is too loose** (confirmed twice 2026-10-16): require EVERY failure
   line to be whitelisted, and add `MasterLimiter_CapsTheLiveMix_OnThePipe` +
   `RealMouseDrag_OnTheLayerList_PersistsTheReorder` to the list.