Fix medium-severity spec drift across 17 specs

- authentication-methods: document completeAuth mode param ("redirect"|"json");
  clarify add-passkey nudge (no dismiss mechanism, disappears on passkey add)
- journal-auth: session maxAge is 30 days; terms allow-list uses /legal/ prefix
  matching (broader than fixed list of paths)
- session-notes: mark awareness isolation and UndoManager isolation as not yet
  implemented (shared instances in current code)
- activity-feed: add fan-out scenario for visibility change to public
- explore: note that ?perPage is not yet implemented (hardcoded page size)
- multi-day-routes: add per-day GPX track split scenario (splitByDays option);
  document overnight vs isDayBreak naming gap
- osm-poi-overlays: debounce is 800ms + 2000ms min interval (not 500ms);
  retry is not automatic (fires on next viewport change)
- brouter-integration: rate limit corrected to 300/hour; add segment-cache
  requirement (client caches per-pair segments)
- wahoo-route-push: OAuth state shape uses camelCase (returnTo, pushAfter
  object) not snake_case with push_after boolean
- komoot-import: document noop adapter / ConnectedServiceManager bypass;
  note four Komoot-specific routes that bypass the generic OAuth framework
- background-jobs: exponential backoff not wired (retryLimit only); add SIGINT
- connected-services: add revoked status; name ConnectionNotActiveError
- infrastructure: add INTEGRATION_SECRET and SENTRY_DSN to env var lists;
  split secret decryption scenario by workflow (cd-apps vs cd-infra)
- secret-management: correct CD decryption — cd-apps only decrypts app.env;
  cd-infra decrypts both
- transactional-emails: welcome email is async (pg-boss job); magic-link email
  includes 6-digit numeric code
- journal-route-detail: websites are https: links (not mailto:); opening_hours
  is also displayed
- local-dev-environment: add mobile app (Expo) dev commands

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

openspec/specs/multi-day-routes/spec.md

@@ -52,3 +52,14 @@ Day structure SHALL be preserved in GPX exports via waypoint type elements.
 - **WHEN** a user exports a plan with overnight waypoints
 - **THEN** overnight waypoints include a `<type>overnight</type>` element in the GPX
 - **AND** reimporting the GPX restores the day structure
+
+#### Scenario: Per-day GPX track splitting
+- **WHEN** `generateGpx` is called with `splitByDays: true`
+- **THEN** the GPX output contains separate `<trk>` elements for each day's segment rather than a single track
+- **AND** each `<trk>` is labelled with the day number
+
+Note: the single-track export (without `splitByDays`) is the default. The per-day split is available as an option on the GPX generator and is the recommended format for multi-day exports to head units.
+
+### Note on overnight vs isDayBreak naming
+
+The Yjs wire format stores the flag as `overnight: true` on the waypoint Y.Map entry. The TypeScript interface exposes it as `isDayBreak` (a comment in `waypoint-ymap.ts` documents `overnight` as the legacy wire name). Spec scenarios use `overnight` to refer to the wire-level concept; TypeScript code uses `isDayBreak`.