Refactor config to use test_default

Introduced a `test_default` method to `Config` to provide sane defaults
for integration tests. This refactors several test files to use this new
method, reducing boilerplate and improving maintainability.

Added `LLM_TIMEOUT_SECONDS` to the environment variables and `Config`
struct.

server/tests/transcribe_test.rs

@@ -1,7 +1,6 @@
 use std::path::PathBuf;
 use std::time::Duration;
 
-use std::collections::HashMap;
 use std::sync::Arc;
 
 use doctate_server::config::{Config, User, WhisperUserSettings};
@@ -249,11 +248,6 @@ async fn recovery_enqueues_only_pending_recordings() {
 
 fn test_config_with_whisper(whisper_url: String) -> Arc<Config> {
     Arc::new(Config {
-        server_port: 3000,
-        data_path: "/tmp".into(),
-        log_level: "info".into(),
-        log_path: "/tmp".into(),
-        log_max_days: 90,
         users: vec![User {
             slug: "dr_test".into(),
             api_key: "k".into(),
@@ -261,22 +255,12 @@ fn test_config_with_whisper(whisper_url: String) -> Arc<Config> {
             role: "doctor".into(),
             whisper: Default::default(),
         }],
-        api_keys: HashMap::new(),
-        retention_audio_days: 30,
-        retention_transcript_days: 30,
-        retention_document_days: 0,
         whisper_url,
         whisper_timeout_seconds: 5,
         // Ollama URL is irrelevant — worker never reaches it in the failure path.
         ollama_url: "http://127.0.0.1:1".into(),
         ollama_model: "test".into(),
-        ollama_keep_alive: 0,
-        llm_url: String::new(),
-        llm_api_key: String::new(),
-        llm_model: String::new(),
-        llm_temperature: 0.0,
-        session_timeout_hours: 8,
-        cookie_secure: false,
+        ..Config::test_default()
     })
 }