fix(infra): use postgres -c flags instead of config_file override

The config_file override replaced the entire default PostgreSQL config
including listen_addresses, breaking inter-container communication.
Use inline -c flags instead which only override specific parameters.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.macmini.yml

@@ -27,7 +27,6 @@ services:
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-mana123}
     volumes:
       - /Volumes/ManaData/postgres:/var/lib/postgresql/data
-      - ./docker/postgres/postgresql.conf:/etc/postgresql/conf.d/custom.conf:ro
     ports:
       - "5432:5432"
     healthcheck:
@@ -37,7 +36,14 @@ services:
       retries: 5
     command: >
       postgres
-      -c 'config_file=/etc/postgresql/conf.d/custom.conf'
+      -c shared_buffers=512MB
+      -c effective_cache_size=2GB
+      -c work_mem=16MB
+      -c maintenance_work_mem=128MB
+      -c max_wal_size=1GB
+      -c max_wal_senders=3
+      -c log_min_duration_statement=1000
+      -c log_checkpoints=on
 
   # PostgreSQL Backup — hourly pg_dumpall + daily pg_basebackup
   # Retention: 48 hourly dumps + 30 daily base backups

docker/postgres/postgresql.conf

@@ -1,6 +1,9 @@
 # PostgreSQL Performance Tuning for Mac Mini (16GB RAM)
 # Shared with ~70 other containers, so conservative settings
 
+# Network (required for Docker inter-container communication)
+listen_addresses = '*'
+
 # Performance
 shared_buffers = 512MB
 effective_cache_size = 2GB