mcp: reuse go-mcp library for MCP server implementation

Replaces odek's hand-rolled MCP server (internal/mcp/mcp.go) with a
thin adapter over github.com/BackendStack21/go-mcp v1.1.0.

Changes:
- internal/mcp/mcp.go: rewritten as ~130-line adapter wrapping gomcp.Server
- Removed duplicated JSON-RPC/MCP protocol types (~230 lines of protocol code)
- Startup logging moved from cmd/odek/mcp.go into Server.Run()
- Added go-mcp as direct dependency (21no.de ecosystem)
- All 14 existing tests pass unchanged

go-mcp provides: JSON-RPC 2.0 dispatch, init tracking, ping, tool/resource/prompt
handlers, protocol version 2025-03-26, isError:true for tool errors.

Author: jkyberneees

cmd/odek/mcp.go

@@ -113,17 +113,5 @@ Flags:
 	// Create and run the MCP server
 	version := getVersion()
 	server := mcp.NewServer(version, nativeTools, os.Stdin, os.Stdout)
-
-	// Log startup to stderr (stdin/stdout are for MCP protocol)
-	fmt.Fprintf(os.Stderr, "odek mcp ⚡  MCP server starting (v%s)\n", version)
-	fmt.Fprint(os.Stderr, "  Tools: ")
-	for i, t := range nativeTools {
-		if i > 0 {
-			fmt.Fprint(os.Stderr, ", ")
-		}
-		fmt.Fprint(os.Stderr, t.Name)
-	}
-	fmt.Fprintln(os.Stderr)
-
 	return server.Run(context.Background())
 }

go.mod

@@ -3,11 +3,10 @@ module github.com/BackendStack21/kode
 go 1.25.0
 
 require (
+	github.com/BackendStack21/go-mcp v1.1.0
 	github.com/BackendStack21/go-vector v1.1.1
 	golang.org/x/net v0.54.0
+	golang.org/x/term v0.43.0
 )
 
-require (
-	golang.org/x/sys v0.44.0 // indirect
-	golang.org/x/term v0.43.0 // indirect
-)
+require golang.org/x/sys v0.44.0 // indirect

go.sum

@@ -1,3 +1,5 @@
+github.com/BackendStack21/go-mcp v1.1.0 h1:NQStOkqUWjzzzmySnfFHvPKhbKr92iBuPJjkNpb0MIU=
+github.com/BackendStack21/go-mcp v1.1.0/go.mod h1:RKFw6nrl6ySQqqrR8KtG7HYZ/heyyjT8SjiEtlbTMY8=
 github.com/BackendStack21/go-vector v1.1.1 h1:sycI+a/ifT2DD3kdH0HleWtjKmIVNutvL/pgOL9qTA8=
 github.com/BackendStack21/go-vector v1.1.1/go.mod h1:+IzfAFO4m6xrjsOhZsiTAbMbm8+hX0d9C1uD0SGPzHc=
 golang.org/x/net v0.54.0 h1:2zJIZAxAHV/OHCDTCOHAYehQzLfSXuf/5SoL/Dv6w/w=