feat: Add comprehensive API client modules and JWT authentication to Rust SDK

- Add hmac, sha2, and base64 dependencies to Cargo.toml for JWT support
- Add README.md with installation instructions, architecture overview, and API examples for all SDK modules
- Add AuthProvider class with API key and JWT token support (generate_jwt_token, validate_jwt_token, get_headers, clear_token_cache methods)
- Add HTTPClient base class with retry logic, error handling, and timeout management
- Add SubscriberAPI module

sdk/rust/README.md

@@ -0,0 +1,238 @@
+# Telecom Platform Rust SDK
+
+Async Rust SDK for the Telecom Platform with full type safety and modern async/await support.
+
+## Features
+
+- **Modular Architecture**: Separate modules for authentication, HTTP client, and API services
+- **Async/Await Support**: Full async/await support with tokio
+- **Type Safety**: Strong typing with Rust structs and enums
+- **Error Handling**: Comprehensive error handling with custom error types
+- **Retry Logic**: Built-in retry mechanism with exponential backoff
+- **Context Support**: Full context.Context support for cancellation
+
+## Installation
+
+Add to your `Cargo.toml`:
+
+```toml
+[dependencies]
+telecom-sdk = { path = "../sdk/rust" }
+```
+
+Or install from source:
+
+```bash
+cd sdk/rust
+cargo build
+```
+
+## Architecture
+
+The SDK is organized into modular components:
+
+- `auth.rs` - Authentication provider handling API keys and JWT tokens
+- `client.rs` - HTTP client with retry logic and authentication
+- `error.rs` - Error types for the SDK
+- `types.rs` - Data structures and type definitions
+- `api/` - Directory containing API modules:
+  - `subscribers.rs` - Subscriber management API
+  - `usage.rs` - Usage tracking API
+  - `payments.rs` - Payment processing API
+  - `rating_plans.rs` - Rating plan management API
+  - `system.rs` - System monitoring API
+  - `graphql.rs` - GraphQL query execution
+  - `mod.rs` - Module exports
+
+## Quick Start
+
+```rust
+use telecom_sdk::{TelecomClient, Config};
+use tokio;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let config = Config {
+        api_url: "http://localhost:8000".to_string(),
+        api_key: Some("your-api-key".to_string()),
+        ..Default::default()
+    };
+
+    let client = TelecomClient::new(config).await?;
+    
+    // Get subscriber
+    let subscriber = client.subscribers.get(1).await?;
+    println!("Subscriber: {} {}", subscriber.first_name, subscriber.last_name);
+    
+    // List subscribers
+    let list = client.subscribers.list(1, 50, None).await?;
+    println!("Total subscribers: {}", list.total);
+    
+    Ok(())
+}
+```
+
+## API Reference
+
+### Configuration
+
+```rust
+let config = Config {
+    api_url: "http://localhost:8000".to_string(),
+    api_key: Some("your-api-key".to_string()),
+    jwt_secret: Some("your-jwt-secret".to_string()),
+    timeout: Some(Duration::from_secs(30)),
+    max_retries: Some(3),
+    retry_delay: Some(Duration::from_secs(1)),
+};
+```
+
+### Subscriber Management
+
+```rust
+// Get subscriber
+let subscriber = client.subscribers.get(1).await?;
+
+// List subscribers
+let list = client.subscribers.list(1, 50, Some("active".to_string())).await?;
+
+// Create subscriber
+let request = CreateSubscriberRequest {
+    imsi: "208930000000001".to_string(),
+    msisdn: "+1234567890".to_string(),
+    first_name: "John".to_string(),
+    last_name: "Doe".to_string(),
+    email: "[email protected]".to_string(),
+    plan_id: 1,
+};
+let subscriber = client.subscribers.create(request).await?;
+
+// Update subscriber
+let update = UpdateSubscriberRequest {
+    first_name: Some("Jane".to_string()),
+    ..Default::default()
+};
+let subscriber = client.subscribers.update(1, update).await?;
+
+// Delete subscriber
+client.subscribers.delete(1).await?;
+
+// Suspend subscriber
+client.subscribers.suspend(1).await?;
+
+// Activate subscriber
+client.subscribers.activate(1).await?;
+```
+
+### Usage Management
+
+```rust
+use std::time::{Duration, SystemTime};
+
+// Get usage stats
+let start_date = SystemTime::now() - Duration::from_secs(30 * 24 * 60 * 60);
+let end_date = SystemTime::now();
+let stats = client.usage.get_stats(1, start_date, end_date).await?;
+
+// List usage events
+let events = client.usage.list_events(1, Some("data".to_string()), 1, 50).await?;
+
+// Get real-time usage
+let realtime = client.usage.get_real_time(1).await?;
+```
+
+### Payment Management
+
+```rust
+// Create payment transaction
+let transaction = client.payments.create_transaction(CreatePaymentTransactionRequest {
+    subscriber_id: "1".to_string(),
+    amount: 25.00,
+    currency: "USD".to_string(),
+    gateway: "stripe".to_string(),
+    metadata: None,
+}).await?;
+
+// Get transaction
+let transaction = client.payments.get_transaction("txn-123".to_string()).await?;
+
+// List transactions
+let transactions = client.payments.list_transactions(1, Some("completed".to_string()), 1, 50).await?;
+```
+
+### Rating Plans
+
+```rust
+// List rating plans
+let plans = client.rating_plans.list().await?;
+
+// Get specific plan
+let plan = client.rating_plans.get("plan-123".to_string()).await?;
+```
+
+### System Management
+
+```rust
+// Get system stats
+let stats = client.system.get_stats().await?;
+
+// Get health status
+let health = client.system.get_health().await?;
+```
+
+### GraphQL
+
+```rust
+// Execute GraphQL query
+let query = r#"
+    query GetSubscribers($first: Int) {
+        subscribers(first: $first) {
+            id
+            firstName
+            lastName
+        }
+    }
+"#;
+
+let variables = serde_json::json!({"first": 10});
+let result = client.graphql.execute(query, Some(variables)).await?;
+```
+
+## Error Handling
+
+```rust
+use telecom_sdk::TelecomError;
+
+match client.subscribers.get(1).await {
+    Ok(subscriber) => println!("Subscriber: {}", subscriber.first_name),
+    Err(TelecomError::AuthenticationError) => println!("Authentication failed"),
+    Err(TelecomError::APIError(msg)) => println!("API error: {}", msg),
+    Err(TelecomError::NetworkError(msg)) => println!("Network error: {}", msg),
+    Err(e) => println!("Error: {}", e),
+}
+```
+
+## Development
+
+### Running Tests
+
+```bash
+cargo test
+```
+
+### Building
+
+```bash
+cargo build --release
+```
+
+### Code Style
+
+```bash
+cargo fmt
+cargo clippy
+```
+
+## License
+
+This SDK is licensed under the MIT License.