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/upload_test.rs

@@ -14,11 +14,7 @@ fn test_config() -> Arc<Config> {
         uuid::Uuid::new_v4()
     ));
     Arc::new(Config {
-        server_port: 3000,
         data_path,
-        log_level: "info".into(),
-        log_path: "/tmp/doctate-test/logs".into(),
-        log_max_days: 90,
         users: vec![User {
             slug: "dr_test".into(),
             api_key: "test-key-123".into(),
@@ -27,20 +23,7 @@ fn test_config() -> Arc<Config> {
             whisper: Default::default(),
         }],
         api_keys: HashMap::from([("test-key-123".into(), "dr_test".into())]),
-        retention_audio_days: 30,
-        retention_transcript_days: 30,
-        retention_document_days: 0,
-        whisper_url: "http://localhost:10300".into(),
-        whisper_timeout_seconds: 120,
-        ollama_url: "http://localhost:11434".into(),
-        ollama_model: "gemma3:4b".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()
     })
 }