feat(docker): add Docker Compose for local development with PostGIS

[NteinPrecious]

Summary

Closes #91

Adds a root-level docker-compose.yml for one-command local development, and a Backend/Dockerfile.dev for hot-reload development. Also fixes the existing infrastructure/docker/ setup which was using plain Postgres without PostGIS — a hard requirement for the app's geospatial queries.

Changes

New files

docker-compose.yml (root — local dev entry point)

• Uses postgis/postgis:16-3.4-alpine so PostGIS is available immediately
• Backend service mounts source code and runs npm run start:dev (hot reload via NestJS watch mode)
• Database env vars (DATABASE_HOST, DATABASE_PORT, etc.) match what the backend expects
• Supports an optional ./Backend/.env override via env_file
• Postgres healthcheck gates backend startup

Backend/Dockerfile.dev

• Lightweight dev image (node:20-alpine) — installs all deps and starts in watch mode
• Distinct from the multi-stage production backend.Dockerfile

Updated files

infrastructure/docker/postgres-init.sql

• Added CREATE EXTENSION IF NOT EXISTS postgis and postgis_topology — without these the app's PostGIS migrations and ST_DWithin queries fail on first boot

infrastructure/docker/docker-compose.yml

• Swapped postgres:16-alpine → postgis/postgis:16-3.4-alpine
• Replaced DATABASE_URL (not used by the backend) with the individual DATABASE_* env vars the app actually reads
• Mounts the init SQL so PostGIS extensions are bootstrapped on first run

Usage

# copy and fill in optional vars (Pinata, Stellar) — DB vars are pre-set by compose
cp Backend/.env.example Backend/.env

# start everything
docker compose up --build

# backend available at http://localhost:3000
# swagger docs at   http://localhost:3000/api/docs
# metrics at        http://localhost:3000/metrics

Test plan

• docker compose up --build — postgres and backend both come up healthy
• curl http://localhost:3000/health — returns { "status": "ok" }
• Edit a source file — confirm NestJS hot reload picks up the change without restarting the container
• docker compose down -v && docker compose up --build — clean boot with PostGIS extensions created on first run (check logs for CREATE EXTENSION)