fix: reduce reconnect redeploy and metrics load (#476)

* fix: reduce reconnect redeploy and metrics load

Throttle node-online redeploy retries and lower the agent metric cadence so brief reconnect churn no longer fans out into repeated runtime syncs and backend connection pressure.

* docs: add follow-up implementation design notes

Document the planned flow upload batching work and the local remote-address toggle so the next changesets can implement them against an agreed design.

go-backend/internal/store/repo/repository_pool_test.go

@@ -0,0 +1,32 @@
+package repo
+
+import (
+	"testing"
+
+	gsqlite "github.com/glebarez/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+)
+
+func TestConfigurePostgresPoolSetsMaxOpenConnections(t *testing.T) {
+	db, err := gorm.Open(gsqlite.Open(":memory:"), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+
+	sqlDB, err := db.DB()
+	if err != nil {
+		t.Fatalf("db handle: %v", err)
+	}
+	t.Cleanup(func() {
+		_ = sqlDB.Close()
+	})
+
+	configurePostgresPool(sqlDB)
+
+	if got := sqlDB.Stats().MaxOpenConnections; got != defaultPostgresMaxOpenConns {
+		t.Fatalf("expected max open conns %d, got %d", defaultPostgresMaxOpenConns, got)
+	}
+}