Integrate gaza-geo-sync

Goal: live positions travel as ~7 bytes per object instead of ~45–100 bytes of JSON, without breaking any existing client. JSON stays the default; binary only when a client asks.

Source of truth: https://github.com/AQaddora/gaza-geo-sync (README, docs/MIGRATION.md, templates/). If the repo is vendored or installed, read src/codec.ts header comment for the byte layout.

Steps

1. Install. Either npm install github:AQaddora/gaza-geo-sync (builds on install), or vendor the four files src/bytes.ts src/codec.ts src/sync.ts src/client.ts (+ src/server.ts server-side) into e.g. src/lib/geo-sync/. Zero runtime dependencies; server.ts needs node:zlib.
2. One shared codec. Copy templates/geo-codec.ts. Set south/west to the south-west corner of the area most points fall in. With the default scale: 1e5 and offsetBytes: 2 the cheap box is ≈0.655° per side (≈73 km N–S); larger areas → offsetBytes: 3 or scale: 1e4. Points outside still work (they cost a few bytes more). Server and client must import the same file.
3. Stable small numbers. Each tracked object needs a small integer n that never changes: add an additive DB column (Postgres seq SERIAL UNIQUE, MySQL AUTO_INCREMENT, SQLite rowid). Never reuse a number for a different id. Send [n, id] pairs (index) on a first sync.
4. Server route. Adapt templates/nextjs-route.ts (App Router) or templates/express-server.ts. Use positionsReply(...); it negotiates on Accept, sets Vary: Accept, Accept-Encoding, gzips binary only when smaller. Keep the JSON branch byte-for-byte compatible with what clients already parse — add fields, never rename.
5. Client. Replace the positions fetch with fetchPositions(url, { codec, idOf }) (or templates/use-live-positions.ts). It sends Accept: application/octet-stream, application/json;q=0.5 and always resolves to the JSON shape, so caches and screens stay unchanged. Persist payload.index next to your cached records; when unknown > 0, drop the cursor so the next request is a full sync.
6. Uploads (optional). For a phone sending its GPS point, use createPointSender or templates/use-point-sender.ts and readPointBody server-side (templates/nextjs-point-route.ts). Answer binary uploads with 204. Old servers answering 400/415 switch the sender to JSON.
7. Service worker. Do not cache the positions endpoint and never queue point uploads offline (templates/service-worker-cache.js).
8. Verify with the binary-sync-verify skill before calling it done.

Rules

• JSON fallback is not optional. curl, old app versions and debugging must keep working.
• Bump profile in the codec options whenever any codec option changes.
• Do not binary-encode text-heavy, diffed data (chat, bookings): gzip'd JSON is fine there.
• Never log decoded coordinates of real users.