[codex] Add SiliconFlow provider support

[Lee-take]

Summary

• Adds SiliconFlow as a first-class provider across CLI, config loading, secrets, TUI selection, docs, and examples.
• Wires provider defaults, environment variable overrides, model alias normalization, and stored API key lookup.
• Treats SiliconFlow streamed reasoning content like other DeepSeek-compatible providers.

Fixes #1710

Validation

• cargo fmt --check
• git diff --check
• cargo check -p deepseek-config
• cargo check -p deepseek-secrets
• cargo check -p deepseek-tui
• cargo check -p deepseek-tui-cli
• cargo test -p deepseek-config siliconflow -- --nocapture
• cargo test -p deepseek-secrets siliconflow -- --nocapture

[gemini-code-assist]

Code Review

This pull request adds support for SiliconFlow as a new model provider, updating the CLI, TUI, and documentation to handle SiliconFlow-specific configurations and environment variables. Feedback was provided regarding the model normalization logic to ensure that reasoning-capable models are correctly mapped to the Pro model instead of the Flash model.

[gemini-code-assist]

The model aliases deepseek-reasoner and deepseek-r1 should be mapped to the Pro model (DEFAULT_SILICONFLOW_MODEL) rather than the Flash model, as they represent reasoning-capable models. Additionally, deepseek-v3.2 appears to be a typo for deepseek-v3 (which is already present) or perhaps deepseek-v2.5.

Suggested change

	(ProviderKind::Siliconflow, "deepseek-v4-pro" | "deepseek-v4pro") => {
	DEFAULT_SILICONFLOW_MODEL.to_string()
	}
	(
	ProviderKind::Siliconflow,
	"deepseek-v4-flash" | "deepseek-v4flash" | "deepseek-chat" | "deepseek-reasoner"
	| "deepseek-r1" | "deepseek-v3" | "deepseek-v3.2",
	) => DEFAULT_SILICONFLOW_FLASH_MODEL.to_string(),
	(
	ProviderKind::Siliconflow,
	"deepseek-v4-pro" | "deepseek-v4pro" | "deepseek-reasoner" | "deepseek-r1",
	) => DEFAULT_SILICONFLOW_MODEL.to_string(),
	(
	ProviderKind::Siliconflow,
	"deepseek-v4-flash" | "deepseek-v4flash" | "deepseek-chat" | "deepseek-v3",
	) => DEFAULT_SILICONFLOW_FLASH_MODEL.to_string(),

[Lee-take]

Fixed in 89aa47a2.

• deepseek-reasoner and deepseek-r1 now map to DEFAULT_SILICONFLOW_MODEL.
• deepseek-v3.2 is no longer treated as a SiliconFlow Flash alias; it is preserved as an explicit model value.
• Added config tests for both behaviors.

Validation: cargo test -p deepseek-config siliconflow -- --nocapture, cargo check -p deepseek-config, cargo check -p deepseek-tui-cli.

[Lee-take]

Addressed the SiliconFlow model alias feedback in the latest push:

• deepseek-reasoner and deepseek-r1 now normalize to the Pro model (DEFAULT_SILICONFLOW_MODEL).
• deepseek-v3.2 is no longer remapped to Flash for SiliconFlow; unknown DeepSeek versions are preserved.
• Added targeted config tests for both behaviors.

Validation:

• cargo fmt --check
• cargo test -p deepseek-config siliconflow -- --nocapture
• cargo check -p deepseek-config
• git diff --check
• cargo check -p deepseek-tui-cli