adding downloadable_model and more downloadable_model python binding

Cargo.toml

@@ -36,6 +36,7 @@ members = [
 xmllint = ["proj"]
 gtfs = []
 parser = []
+downloadable = []
 
 [dependencies]
 anyhow = "1"
@@ -69,6 +70,8 @@ wkt = "0.10"
 zip = { version = "2", default-features = false, features = ["deflate"] }
 git-version = "0.3"
 pyo3 = "0.23.4"
+reqwest = { version = "0.12.12", features = ["json"] }
+tokio = "1.43.0"
 
 [[test]]
 name = "write_netex_france"
@@ -80,3 +83,6 @@ approx = "0.5"
 log = "0.4"
 rust_decimal_macros = "1"
 testing_logger = "0.1"
+mockito = "0.31"
+tokio = { version = "1.0", features = ["full", "test-util"] }
+futures = "0.3"

downloadable_model_graph.md

@@ -0,0 +1,51 @@
+```mermaid
+graph TD
+    A[DownloadableTransitModel] --> B[ModelConfig]
+    A --> C[NavitiaConfig]
+    A --> D[Downloader]
+    A --> E[Arc<RwLock<Model>>]
+    A --> F[Arc<Mutex<String>>]
+    
+    subgraph Initialization
+        G[Start] --> H[initialize_model]
+        H --> I[get_remote_version]
+        I --> J[Navitia API]
+        H --> K[run_download]
+        K --> L[Downloader]
+        H --> M[ntfs::read]
+    end
+    
+    subgraph Background Updater
+        N[start_background_updater] --> O[check_and_update]
+        O --> P[get_remote_version]
+        O --> Q{Version Newer?}
+        Q -->|Yes| R[run_download]
+        Q -->|No| S[Return false]
+        R --> T[ntfs::read]
+        T --> U[Atomic Model Swap]
+        U --> V[Version Update]
+    end
+    
+    subgraph External Components
+        J -->|HTTP GET| W((Navitia Server))
+        L -->|Storage| X[(S3/File System)]
+        M --> Y[NTFS Parser]
+    end
+    
+    subgraph Concurrency
+        E -.->|RwLock| Z[Thread-safe Reads]
+        E -.->|Write Lock| AA[Atomic Updates]
+        F -.->|Mutex| AB[Version Safety]
+        N --> AC[Tokio Spawn]
+    end
+    
+    style A fill:#f9f,stroke:#333
+    style B fill:#ccf,stroke:#333
+    style C fill:#ccf,stroke:#333
+    style D fill:#cfc,stroke:#333
+    style J fill:#fcc,stroke:#333
+    style L fill:#fcc,stroke:#333
+    style W fill:#cff,stroke:#333
+    style X fill:#cff,stroke:#333
+    style Y fill:#cff,stroke:#333
+```