feat: add deepseek provider scaffolding

src/config/settings.rs

@@ -0,0 +1,46 @@
+use thiserror::Error;
+
+const DEFAULT_DEEPSEEK_BASE_URL: &str = "https://api.deepseek.com";
+const DEFAULT_DEEPSEEK_MODEL: &str = "deepseek-chat";
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct DeepSeekSettings {
+    pub api_key: String,
+    pub base_url: String,
+    pub model: String,
+}
+
+impl DeepSeekSettings {
+    pub fn from_env() -> Result<Self, ConfigError> {
+        let api_key = std::env::var("DEEPSEEK_API_KEY")
+            .map_err(|_| ConfigError::MissingEnv("DEEPSEEK_API_KEY"))?;
+        let base_url = std::env::var("DEEPSEEK_BASE_URL")
+            .unwrap_or_else(|_| DEFAULT_DEEPSEEK_BASE_URL.to_string());
+        let model =
+            std::env::var("DEEPSEEK_MODEL").unwrap_or_else(|_| DEFAULT_DEEPSEEK_MODEL.to_string());
+
+        if api_key.trim().is_empty() {
+            return Err(ConfigError::EmptyValue("DEEPSEEK_API_KEY"));
+        }
+        if base_url.trim().is_empty() {
+            return Err(ConfigError::EmptyValue("DEEPSEEK_BASE_URL"));
+        }
+        if model.trim().is_empty() {
+            return Err(ConfigError::EmptyValue("DEEPSEEK_MODEL"));
+        }
+
+        Ok(Self {
+            api_key,
+            base_url,
+            model,
+        })
+    }
+}
+
+#[derive(Debug, Error, Clone, PartialEq, Eq)]
+pub enum ConfigError {
+    #[error("missing environment variable: {0}")]
+    MissingEnv(&'static str),
+    #[error("environment variable must not be empty: {0}")]
+    EmptyValue(&'static str),
+}