split: server REST endpoints + rate limiting

server.rs router rewrite, auth.rs, device_id_header.rs, requests.rs,
responses.rs, plus per-endpoint changes: create/update/delete_document,
fetch_document_version{,_content,s}, fetch_latest_documents, index.rs.
Adds: fetch_vault_history, list_vaults, rate_limit (new files).

sync-server/src/server/fetch_document_versions.rs

@@ -0,0 +1,42 @@
+use axum::{
+    Json,
+    extract::{Path, State},
+};
+use log::debug;
+use serde::Deserialize;
+
+use crate::{
+    app_state::{
+        AppState,
+        database::models::{DocumentId, DocumentVersionWithoutContent, VaultId},
+    },
+    errors::{SyncServerError, server_error},
+    utils::normalize::normalize,
+};
+
+#[derive(Deserialize)]
+pub struct FetchDocumentVersionsPathParams {
+    #[serde(deserialize_with = "normalize")]
+    vault_id: VaultId,
+
+    document_id: DocumentId,
+}
+
+#[axum::debug_handler]
+pub async fn fetch_document_versions(
+    Path(FetchDocumentVersionsPathParams {
+        vault_id,
+        document_id,
+    }): Path<FetchDocumentVersionsPathParams>,
+    State(state): State<AppState>,
+) -> Result<Json<Vec<DocumentVersionWithoutContent>>, SyncServerError> {
+    debug!("Fetching all versions for document `{document_id}` in vault `{vault_id}`");
+
+    let versions = state
+        .database
+        .get_document_versions(&vault_id, &document_id, None)
+        .await
+        .map_err(server_error)?;
+
+    Ok(Json(versions))
+}