Go: add stream / think chat (#14242)

### What problem does this PR solve?

1. Supports stream and non-stream chat
2. Supports think and non-think chat
3. List supported models from DeepSeek service. (This command can be
used to verify the API validity)

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/cli/parser.go

@@ -190,6 +190,8 @@ func (p *Parser) parseUserCommand() (*Command, error) {
 		return p.parseEnableCommand()
 	case TokenDisable:
 		return p.parseDisableCommand()
+	case TokenStream:
+		return p.parseStreamCommand()
 	case TokenChat:
 		return p.parseChatCommand()
 	case TokenThink: