Park mobile-activity-recording + mobile-nearby-sync under docs/ideas

Both are blocked on the mobile-app foundation and on a user base that
actually records activities or needs offline peer sync. With 3 users
and 0 activities on prod today, these are engineering for a
hypothetical population.

Move the artifact sets out of openspec/changes/ (so openspec list
stays clean) and under docs/ideas/ where self-host-overpass already
lives. Each gets a short README documenting:

- current parked status
- revive triggers (when should we look at this again?)
- key constraints not to rediscover (background-GPS privacy review;
  BLE dev-build requirement; QR-only subset as a cheaper path)

Reviving is `git mv docs/ideas/<name> openspec/changes/<name>` and
running /opsx:apply, same pattern as self-host-overpass.

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

docs/ideas/mobile-activity-recording/README.md

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+# mobile-activity-recording (parked)
+
+OpenSpec change for recording GPS activities on-device in the mobile app
+(ride/hike tracking, live stats, save as Journal activity, HealthKit /
+Health Connect export). Moved here from `openspec/changes/` so it does not
+clutter the active change list; revive by moving the directory back under
+`openspec/changes/` when ready to implement.
+
+## Status
+
+**Parked.** Blocked on `mobile-app` (the foundation change) landing first,
+and on there being enough Journal users actually logging activities to
+justify the native-recording complexity. At the current user count (3) and
+activity count (0), shipping this would be writing code for nobody.
+
+## When to revive
+
+Revisit once **any** of these is true:
+
+- The mobile app is live and users are asking to record from the phone
+  instead of importing from Wahoo/Garmin/Komoot later
+- The web Journal has a meaningful stream of imported activities, so the
+  feature lands into an existing behaviour rather than inventing one
+- A specific user request justifies the iOS/Android background-location
+  privacy review (App Store's bar for background GPS is high)
+
+## Key constraints to remember
+
+- **Background GPS requires explicit user consent + justification** on iOS
+  and Android. App Store privacy review will scrutinise this.
+- **Dependencies**: `expo-location` for the track, plus `expo-health` (or
+  equivalent) for HealthKit / Health Connect integration.
+- **Battery**: continuous GPS at high accuracy is a power-hungry path;
+  recording UI needs clear on/off state and resumption.
+
+## What's in the folder
+
+- `proposal.md` — why / what / impact
+- `specs/` — delta specs (would land against a new `mobile-activity-recording` capability)

docs/ideas/mobile-nearby-sync/README.md

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+# mobile-nearby-sync (parked)
+
+OpenSpec change for sharing routes between nearby devices without internet
+(BLE-based peer sync + QR-code waypoint fallback) in the mobile app.
+Moved here from `openspec/changes/` so it does not clutter the active
+change list; revive by moving the directory back under
+`openspec/changes/` when ready to implement.
+
+## Status
+
+**Parked.** Blocked on `mobile-app` landing first, and on there being
+enough users actually hiking/bikepacking together to justify the BLE
+complexity. At the current user count (3) this is engineering for a
+hypothetical group trip.
+
+## When to revive
+
+Revisit once **any** of these is true:
+
+- The mobile app is live and users start reporting "we were in a dead zone
+  and couldn't update the route"
+- A group / tour organiser asks specifically for peer-to-peer route sync
+- QR-code waypoint sharing alone (the simpler half of this spec) would
+  cover the need — worth shipping that first as a narrower change
+
+## Key constraints to remember
+
+- **Requires an Expo dev build** — `react-native-ble-plx` isn't available
+  in Expo Go.
+- **iOS + Android BLE APIs differ significantly**; expect platform-specific
+  bugs. Background BLE advertising has battery and OS-lifecycle caveats
+  (iOS suspends advertising when backgrounded after a grace period).
+- **Permissions sprawl**: iOS `NSBluetoothAlwaysUsageDescription`, Android
+  `BLUETOOTH_SCAN` + `BLUETOOTH_CONNECT` + `BLUETOOTH_ADVERTISE`, plus
+  location on older Android.
+- **QR waypoint sharing is an order of magnitude simpler** than BLE and
+  covers a big chunk of the use case — consider extracting that as a
+  separate, earlier change if the need becomes real.
+
+## What's in the folder
+
+- `proposal.md` — why / what / non-goals / impact / future ideas (TXQR)
+- `specs/` — delta specs (would land against a new `mobile-nearby-sync` capability)