chore: unify health check timers across compose and workflows

Docker Compose health checks (all services):
- interval: 5s (was 10-30s)
- timeout: 5s (unified)
- backend start_period: 60s (was 30-180s)

Gitea workflow health check loops:
- Docker healthcheck: 48 attempts x 5s = 4 min (was 24 x 10s)
- Backend health: 12 attempts x 5s = 60s (was 6 x 10s)
- External health: 12 attempts x 5s = 60s (was 6 x 10s)
- Initial waits: 5s (was 10-15s)

Same total wait times, faster detection of success/failure.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.blue-green.yml

@@ -34,7 +34,7 @@ services:
       - mvp-backend-blue
     healthcheck:
       test: ["CMD-SHELL", "curl -sf http://localhost:3000 || exit 1"]
-      interval: 10s
+      interval: 5s
       timeout: 5s
       retries: 3
       start_period: 10s
@@ -89,10 +89,10 @@ services:
       test:
         - CMD-SHELL
         - node -e "require('http').get('http://localhost:3001/health', r => process.exit(r.statusCode===200?0:1)).on('error', () => process.exit(1))"
-      interval: 10s
+      interval: 5s
       timeout: 5s
-      retries: 3
-      start_period: 30s
+      retries: 5
+      start_period: 60s
     deploy:
       resources:
         limits:
@@ -125,7 +125,7 @@ services:
       - mvp-backend-green
     healthcheck:
       test: ["CMD-SHELL", "curl -sf http://localhost:3000 || exit 1"]
-      interval: 10s
+      interval: 5s
       timeout: 5s
       retries: 3
       start_period: 10s
@@ -180,10 +180,10 @@ services:
       test:
         - CMD-SHELL
         - node -e "require('http').get('http://localhost:3001/health', r => process.exit(r.statusCode===200?0:1)).on('error', () => process.exit(1))"
-      interval: 10s
+      interval: 5s
       timeout: 5s
-      retries: 3
-      start_period: 30s
+      retries: 5
+      start_period: 60s
     deploy:
       resources:
         limits: