fix: provisioning race condition and noisy ClickHouse logs

Defer provisionAsync() until after the transaction commits using
TransactionSynchronization.afterCommit(). Previously the @Async thread
raced the @Transactional commit — findById returned null because the
tenant INSERT wasn't visible yet.

Downgrade ClickHouse UNKNOWN_TABLE errors to DEBUG level in
InfrastructureService. These are expected on fresh installs before any
cameleer-server has created the tables.

Make the onboarding slug field read-only (derived from org name).

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

src/main/java/net/siegeln/cameleer/saas/vendor/InfrastructureService.java

@@ -224,7 +224,11 @@ public class InfrastructureService {
                             .put(table, cnt);
                     }
                 } catch (Exception e) {
-                    log.error("Failed to query ClickHouse table '{}' for tenant stats: {}", table, e.getMessage(), e);
+                    if (e.getMessage() != null && e.getMessage().contains("UNKNOWN_TABLE")) {
+                        log.debug("ClickHouse table '{}' does not exist yet — skipping", table);
+                    } else {
+                        log.error("Failed to query ClickHouse table '{}' for tenant stats: {}", table, e.getMessage(), e);
+                    }
                 }
             }
         } catch (Exception e) {
@@ -256,8 +260,12 @@ public class InfrastructureService {
                         result.add(new ChTableStats(table, rs.getLong("cnt")));
                     }
                 } catch (Exception e) {
-                    log.error("Failed to query ClickHouse table '{}' for tenant '{}': {}",
-                        table, tenantId, e.getMessage(), e);
+                    if (e.getMessage() != null && e.getMessage().contains("UNKNOWN_TABLE")) {
+                        log.debug("ClickHouse table '{}' does not exist yet — skipping", table);
+                    } else {
+                        log.error("Failed to query ClickHouse table '{}' for tenant '{}': {}",
+                            table, tenantId, e.getMessage(), e);
+                    }
                 }
             }
         } catch (Exception e) {

src/main/java/net/siegeln/cameleer/saas/vendor/VendorTenantService.java

@@ -26,6 +26,8 @@ import org.springframework.context.annotation.Lazy;
 import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.transaction.support.TransactionSynchronization;
+import org.springframework.transaction.support.TransactionSynchronizationManager;
 
 import java.time.Duration;
 import java.util.List;
@@ -116,9 +118,19 @@ public class VendorTenantService {
                 AuditAction.TENANT_CREATE, "provision:" + tenant.getSlug(),
                 null, null, "SUCCESS", null);
 
-        // 4. Provision server asynchronously (Docker containers, health check, config push)
+        // 4. Provision server asynchronously AFTER transaction commits
+        //    (the async thread needs the tenant row to be visible)
         if (tenantProvisioner.isAvailable()) {
-            self.provisionAsync(tenant.getId(), tenant.getSlug(), tenant.getTier().name(), license.getToken(), actorId);
+            UUID tenantId = tenant.getId();
+            String slug = tenant.getSlug();
+            String tierName = tenant.getTier().name();
+            String token = license.getToken();
+            TransactionSynchronizationManager.registerSynchronization(new TransactionSynchronization() {
+                @Override
+                public void afterCommit() {
+                    self.provisionAsync(tenantId, slug, tierName, token, actorId);
+                }
+            });
         }
 
         return tenant;