Update mc-proxy dependency to v1.2.0, drop replace directive

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

go.mod

@@ -3,7 +3,7 @@ module git.wntrmute.dev/mc/mcp
 go 1.25.7
 
 require (
-	git.wntrmute.dev/mc/mc-proxy v1.1.0
+	git.wntrmute.dev/mc/mc-proxy v1.2.0
 	github.com/pelletier/go-toml/v2 v2.3.0
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/sys v0.42.0
@@ -27,5 +27,3 @@ require (
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect
 )
-
-replace git.wntrmute.dev/mc/mc-proxy => /home/kyle/src/metacircular/mc-proxy