refactor(compose): make app/db ports configurable via DB_PORT and SERVER_PORT

Replace hardcoded port literals with env-driven variables so a single change
in .env reconfigures the full stack consistently. Defaults are unchanged
(DB 5432, app 8765), so existing setups need no .env changes.

- DB_PORT (default 5432): drives the db host<->container port mapping,
  Postgres PGPORT (so it listens on the chosen port), and the app's
  DATABASE_PORT connection setting. Lets deployers avoid a host port conflict
  (e.g. another local Postgres) by setting DB_PORT once.
- SERVER_PORT (default 8765): drives the app host<->container mapping, the
  SERVER_PORT the app listens on, and the healthcheck target URL.
- Applied to both the base (docker-compose.yml) and the dev override
  (docker-compose.dev.yml, tests service) so dev and prod stay in sync.

docker-compose.dev.yml

@@ -23,7 +23,7 @@ services:
     environment:
       # Database Configuration
       DATABASE_HOST: db
-      DATABASE_PORT: "5432"
+      DATABASE_PORT: ${DB_PORT:-5432}
       DATABASE_USER: postgres
       DATABASE_PASSWORD: ${DBPASS}
       DATABASE_NAME: bookhoard
@@ -31,7 +31,7 @@ services:
 
       # Application Configuration
       JWT_SECRET: ${JWT_SECRET}
-      SERVER_PORT: "8765"
+      SERVER_PORT: ${SERVER_PORT:-8765}
 
       # Test Configuration
       TEST_MODE: "true"

docker-compose.yml

@@ -7,13 +7,15 @@ services:
       POSTGRES_DB: bookhoard
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD: ${DBPASS}
+      # PGPORT makes Postgres listen on DB_PORT (kept in sync with the host mapping + app's DATABASE_PORT)
+      PGPORT: ${DB_PORT:-5432}
     volumes:
       - postgres_data:/var/lib/postgresql/data
       - ./database/schema:/docker-entrypoint-initdb.d
       # Make other volumes as needed
       - ./uploads:/app/uploads
     ports:
-      - "5432:5432"
+      - "${DB_PORT:-5432}:${DB_PORT:-5432}"
     healthcheck:
       test: ["CMD-SHELL", "pg_isready -U postgres"]
       interval: 30s
@@ -32,14 +34,14 @@ services:
     environment:
       # Database Configuration
       DATABASE_HOST: db
-      DATABASE_PORT: "5432"
+      DATABASE_PORT: ${DB_PORT:-5432}
       DATABASE_USER: postgres
       DATABASE_PASSWORD: ${DBPASS}
       DATABASE_NAME: bookhoard
 
       # Application Configuration
       JWT_SECRET: ${JWT_SECRET}
-      SERVER_PORT: "8765"
+      SERVER_PORT: ${SERVER_PORT:-8765}
       # IMPORTANT: Device sync requires full URL with protocol
       # Local: http://localhost:8765
       # Local network: http://192.168.1.X:8765
@@ -61,7 +63,7 @@ services:
       # System timezone (fallback for server-side time operations)
       TZ: ${TZ:-UTC}
     ports:
-      - "8765:8765"
+      - "${SERVER_PORT:-8765}:${SERVER_PORT:-8765}"
     depends_on:
       db:
         condition: service_healthy
@@ -69,7 +71,7 @@ services:
       - ./uploads:/app/uploads
       - bookhoard_conversion_cache:/app/cache/kepub
     healthcheck:
-      test: ["CMD-SHELL", "curl -f http://localhost:8765/health || exit 1"]
+      test: ["CMD-SHELL", "curl -f http://localhost:${SERVER_PORT:-8765}/health || exit 1"]
       interval: 30s
       timeout: 5s
       retries: 3