feat: add server lifecycle management and D1 logging

- Add start/stop/reboot endpoints for server power management
- Add D1-based logging system (logs table + db-logger utility)
- Add idempotency_key validation for order deduplication
- Extend VPS provider interface with lifecycle methods

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

src/services/vultr-provider.ts

@@ -134,9 +134,96 @@ export class VultrProvider extends VPSProviderBase {
     }
   }
 
+  async startServer(instanceId: string): Promise<{ success: boolean; error?: string }> {
+    const url = `${this.config.baseUrl}/instances/${instanceId}/start`;
+
+    try {
+      const response = await this.fetchWithRetry(url, {
+        method: 'POST',
+        headers: {
+          Authorization: `Bearer ${this.config.apiKey}`,
+        },
+      });
+
+      // Vultr returns 204 No Content on success
+      if (response.status === 204 || response.ok) {
+        return { success: true };
+      }
+
+      const error = (await response.json()) as VultrError;
+      return {
+        success: false,
+        error: error.error || 'Failed to start instance',
+      };
+    } catch (error) {
+      return {
+        success: false,
+        error: error instanceof Error ? error.message : 'Network error',
+      };
+    }
+  }
+
+  async stopServer(instanceId: string): Promise<{ success: boolean; error?: string }> {
+    const url = `${this.config.baseUrl}/instances/${instanceId}/halt`;
+
+    try {
+      const response = await this.fetchWithRetry(url, {
+        method: 'POST',
+        headers: {
+          Authorization: `Bearer ${this.config.apiKey}`,
+        },
+      });
+
+      // Vultr returns 204 No Content on success
+      if (response.status === 204 || response.ok) {
+        return { success: true };
+      }
+
+      const error = (await response.json()) as VultrError;
+      return {
+        success: false,
+        error: error.error || 'Failed to stop instance',
+      };
+    } catch (error) {
+      return {
+        success: false,
+        error: error instanceof Error ? error.message : 'Network error',
+      };
+    }
+  }
+
+  async rebootServer(instanceId: string): Promise<{ success: boolean; error?: string }> {
+    const url = `${this.config.baseUrl}/instances/${instanceId}/reboot`;
+
+    try {
+      const response = await this.fetchWithRetry(url, {
+        method: 'POST',
+        headers: {
+          Authorization: `Bearer ${this.config.apiKey}`,
+        },
+      });
+
+      // Vultr returns 204 No Content on success
+      if (response.status === 204 || response.ok) {
+        return { success: true };
+      }
+
+      const error = (await response.json()) as VultrError;
+      return {
+        success: false,
+        error: error.error || 'Failed to reboot instance',
+      };
+    } catch (error) {
+      return {
+        success: false,
+        error: error instanceof Error ? error.message : 'Network error',
+      };
+    }
+  }
+
   async getServerStatus(
     instanceId: string
-  ): Promise<{ status: string; ipv4?: string; ipv6?: string }> {
+  ): Promise<{ status: string; power_status?: string; ipv4?: string; ipv6?: string }> {
     const url = `${this.config.baseUrl}/instances/${instanceId}`;
 
     try {
@@ -154,6 +241,7 @@ export class VultrProvider extends VPSProviderBase {
       const data = (await response.json()) as { instance: VultrInstance };
       return {
         status: data.instance.status,
+        power_status: data.instance.power_status,
         ipv4: data.instance.main_ip !== '0.0.0.0' ? data.instance.main_ip : undefined,
         ipv6: data.instance.v6_main_ip || undefined,
       };