fix(compose): health-gate Postgres dependents on real readiness

compose.yml had zero `condition: service_healthy` gates — every
depends_on was a bare list, so dependents waited only for the container
to *start*, not for the service to accept connections. `api`, `git`,
`nessie`, and `polaris` could boot before Postgres was ready.

Add a `pg_isready` healthcheck to postgres (Bitnami image ships it) and
convert those four dependents to the mapping form, gating postgres on
`service_healthy` while keeping other deps at `service_started`.

Validated with `docker compose config`; the four gates resolve to
service_healthy. Runtime-confirm on the next deploy. Follow-up: add
readiness probes + gating for trino/nessie/polaris/rustfs themselves
(their in-container probe tooling needs live verification first).

compose.yml

@@ -139,6 +139,14 @@ services:
       - "promtail=true"
     security_opt:
       - no-new-privileges:true
+    healthcheck:
+      # Gate dependents (git, nessie, polaris, api) on Postgres actually
+      # accepting connections, not just the container having started.
+      test: ["CMD-SHELL", "pg_isready -U postgres -d gitea"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+      start_period: 30s
     restart: unless-stopped
 
   git:
@@ -204,8 +212,10 @@ services:
       - "2222:2222"
       - "3000:3000"
     depends_on:
-      - postgres
-      - rustfs
+      postgres:
+        condition: service_healthy
+      rustfs:
+        condition: service_started
     labels:
       - "promtail=true"
     security_opt:
@@ -399,8 +409,10 @@ services:
       - QUARKUS_OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://otel-collector:4317
       - QUARKUS_OTEL_SERVICE_NAME=nessie
     depends_on:
-      - postgres
-      - rustfs
+      postgres:
+        condition: service_healthy
+      rustfs:
+        condition: service_started
     labels:
       - "promtail=true"
     security_opt:
@@ -461,8 +473,10 @@ services:
       - QUARKUS_OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://otel-collector:4317
       - QUARKUS_OTEL_SERVICE_NAME=polaris
     depends_on:
-      - postgres
-      - rustfs
+      postgres:
+        condition: service_healthy
+      rustfs:
+        condition: service_started
     labels:
       - "promtail=true"
     security_opt:
@@ -528,9 +542,12 @@ services:
     volumes:
       - ./data:/app/data
     depends_on:
-      - postgres
-      - rustfs
-      - nessie
+      postgres:
+        condition: service_healthy
+      rustfs:
+        condition: service_started
+      nessie:
+        condition: service_started
     labels:
       - "promtail=true"
     security_opt: