Add DeepSeek support (#23551)

- Added support for DeepSeek as a new language model provider in Zed
Assistant
- Implemented streaming API support for real-time responses from
DeepSeek models.
- Added a configuration UI for DeepSeek API key management and settings.
- Updated documentation with detailed setup instructions for DeepSeek
integration.
- Added DeepSeek-specific icons and model definitions for seamless
integration into the Zed UI.
- Integrated DeepSeek into the language model registry, making it
available alongside other providers like OpenAI and Anthropic.

Release Notes:

- Added support for DeepSeek to the Assistant.

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/language_models/src/settings.rs

@@ -13,6 +13,7 @@ use crate::provider::{
     anthropic::AnthropicSettings,
     cloud::{self, ZedDotDevSettings},
     copilot_chat::CopilotChatSettings,
+    deepseek::DeepSeekSettings,
     google::GoogleSettings,
     lmstudio::LmStudioSettings,
     ollama::OllamaSettings,
@@ -61,6 +62,7 @@ pub struct AllLanguageModelSettings {
     pub google: GoogleSettings,
     pub copilot_chat: CopilotChatSettings,
     pub lmstudio: LmStudioSettings,
+    pub deepseek: DeepSeekSettings,
 }
 
 #[derive(Default, Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
@@ -72,6 +74,7 @@ pub struct AllLanguageModelSettingsContent {
     #[serde(rename = "zed.dev")]
     pub zed_dot_dev: Option<ZedDotDevSettingsContent>,
     pub google: Option<GoogleSettingsContent>,
+    pub deepseek: Option<DeepseekSettingsContent>,
     pub copilot_chat: Option<CopilotChatSettingsContent>,
 }
 
@@ -162,6 +165,12 @@ pub struct LmStudioSettingsContent {
     pub available_models: Option<Vec<provider::lmstudio::AvailableModel>>,
 }
 
+#[derive(Default, Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
+pub struct DeepseekSettingsContent {
+    pub api_url: Option<String>,
+    pub available_models: Option<Vec<provider::deepseek::AvailableModel>>,
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
 #[serde(untagged)]
 pub enum OpenAiSettingsContent {
@@ -299,6 +308,18 @@ impl settings::Settings for AllLanguageModelSettings {
                 lmstudio.as_ref().and_then(|s| s.available_models.clone()),
             );
 
+            // DeepSeek
+            let deepseek = value.deepseek.clone();
+
+            merge(
+                &mut settings.deepseek.api_url,
+                value.deepseek.as_ref().and_then(|s| s.api_url.clone()),
+            );
+            merge(
+                &mut settings.deepseek.available_models,
+                deepseek.as_ref().and_then(|s| s.available_models.clone()),
+            );
+
             // OpenAI
             let (openai, upgraded) = match value.openai.clone().map(|s| s.upgrade()) {
                 Some((content, upgraded)) => (Some(content), upgraded),