feat: implement gt sling and wisp hook system (gt-qvn7.1)

Phase 1 of tracer bullet: Slinging Handoff

- Add internal/wisp package for ephemeral work attachment
- Add gt sling command to attach work and restart
- Update gt prime to check/burn slung work on hook
- Add .beads-wisp/ to gitignore

go.mod

@@ -18,4 +18,5 @@ require (
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	golang.org/x/sys v0.19.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )