fix(mandrel-mcp-th): shorten invalid keyword for crates.io publishing

- Change 'model-context-protocol' (21 chars) to 'mcp-protocol' (12 chars)
- Crates.io requires keywords to be less than 20 characters
- Fixes publishing error: 'model-context-protocol' is an invalid keyword
- Resolves mandrel-mcp-th v0.4.4 publishing failure

closes #mandrel-mcp-th-keyword-length-issue

Author: milliondreams

crates/mandrel-mcp-th/Cargo.toml

@@ -6,7 +6,7 @@ authors = ["AI Assistant"]
 description = "Mandrel MCP Test Harness - Professional testing and reporting for MCP servers"
 license = "MIT"
 repository = "https://github.com/user/dragonscale"
-keywords = ["mcp", "testing", "protocol", "model-context-protocol"]
+keywords = ["mcp", "testing", "protocol", "mcp-protocol"]
 categories = ["development-tools::testing", "command-line-utilities"]
 
 [[bin]]