Add vendor

Specifically because I want to modify a dependency

vendor/github.com/charmbracelet/x/ansi/doc.go

@@ -0,0 +1,7 @@
+// Package ansi defines common ANSI escape sequences based on the ECMA-48
+// specs.
+//
+// All sequences use 7-bit C1 control codes, which are supported by most
+// terminal emulators. OSC sequences are terminated by a BEL for wider
+// compatibility with terminals.
+package ansi