feat: add streamableHttp transport method support (#20)

Previously, this tool only supported SSE as the transport method for the remote servers it installed via supergateway. This resulted in errors for newer servers using streamable HTTP. This PR addresses this issue by allowing installation of both SSE and HTTP servers. 

There is no way to perfectly detect whether an MCP server uses streamable HTTP or SSE, but we can make a really good guess (the guesses were all perfect in my testing). We still ask the user for confirmation anyway though, just in case it makes a mistake. Claude Code requires the transport method to be specified and has no mechanism for detecting it AFAIK, so this is already an improvement. If the method cannot be guessed, the user is prompted.

Author: Dhravya

README.md

@@ -53,6 +53,50 @@ npx install-mcp https://api.example.com/mcp --client claude \
   --header "X-API-Key: secret-key"
 ```
 
+### Transport Methods for Remote Servers
+
+When installing remote servers (URLs), the CLI needs to know which transport method the server uses. There are two transport methods:
+
+- **Streamable HTTP** (modern, recommended)
+- **SSE** (legacy)
+
+The CLI handles this in several ways:
+
+#### Automatic Detection
+
+By default, the CLI will automatically detect the transport method:
+
+```bash
+npx install-mcp https://api.example.com/mcp --client claude
+# Output: Detecting transport type... this may take a few seconds.
+# Output: We've detected that this server uses the streamable HTTP transport method. Is this correct? (Y/n)
+```
+
+If the detection succeeds, it will ask you to confirm. If you answer "no", it will use the other transport method.
+
+#### Manual Specification
+
+You can skip detection by specifying the transport method directly:
+
+```bash
+# For streamable HTTP servers
+npx install-mcp https://api.example.com/mcp --client claude --transport http
+
+# For legacy SSE servers
+npx install-mcp https://api.example.com/mcp --client claude --transport sse
+```
+
+#### Fallback to Manual Questions
+
+If auto-detection fails, the CLI will ask you directly:
+
+```
+Could not auto-detect transport type, please answer the following questions:
+Does this server support the streamable HTTP transport method? (Y/n)
+```
+
+Note: This only applies to URL-based installations. Package names and custom commands don't require transport selection.
+
 where `<client>` is one of the following:
 
 - `claude`