MCP CLI: return HTTP URL for file downloads instead of gRPC

Description

When the MCP CLI is asked to download files (e.g. PCAP exports), there are currently two download methods: HTTP and gRPC. The gRPC method constantly fails, making downloads unreliable.

The fix is to consolidate on a single download method — HTTP. When a download is requested via MCP, the CLI should return the HTTP download URL to the caller rather than attempting a gRPC-based transfer.

Current behavior

• MCP CLI offers both HTTP and gRPC download paths
• gRPC downloads constantly fail
• Users have to work around the gRPC failures manually

Expected behavior

• MCP CLI returns the HTTP download URL when a file download is requested
• Remove or deprecate the gRPC download path
• Single, reliable download method

Why Is This Needed?

File downloads (especially PCAPs) are a core MCP workflow. The gRPC method is unreliable and adds unnecessary complexity. Consolidating on HTTP simplifies the code and gives users a consistently working download experience.