Feat v0.9.2 Starlark converter consolidation + snapshot cleanup (#75)

Consolidate duplicate Go↔Starlark converters into sandbox/convert.go
and snapshot parsers into models/snapshot.go. Standardize snapshot
creation on wrapped format. Net -393 lines across 21 files.

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

server/triggers/webhook.go

@@ -13,6 +13,7 @@ import (
 	"go.starlark.net/starlark"
 
 	"armature/models"
+	"armature/sandbox"
 )
 
 // HandleWebhook is the Gin handler for inbound webhook triggers.
@@ -152,7 +153,7 @@ func parseWebhookResponse(val starlark.Value) webhookResponse {
 		}
 
 		if bodyVal, found, _ := d.Get(starlark.String("body")); found {
-			resp.body = starlarkToGo(bodyVal)
+			resp.body = sandbox.StarlarkToGo(bodyVal)
 		} else {
 			resp.body = gin.H{"ok": true}
 		}
@@ -168,41 +169,6 @@ func parseWebhookResponse(val starlark.Value) webhookResponse {
 	return webhookResponse{status: 200, body: gin.H{"ok": true}}
 }
 
-// starlarkToGo converts a Starlark value to a Go value (for JSON serialization).
-func starlarkToGo(v starlark.Value) any {
-	switch val := v.(type) {
-	case starlark.NoneType:
-		return nil
-	case starlark.Bool:
-		return bool(val)
-	case starlark.Int:
-		if i, ok := val.Int64(); ok {
-			return i
-		}
-		return val.String()
-	case starlark.Float:
-		return float64(val)
-	case starlark.String:
-		return string(val)
-	case *starlark.List:
-		result := make([]any, val.Len())
-		for i := 0; i < val.Len(); i++ {
-			result[i] = starlarkToGo(val.Index(i))
-		}
-		return result
-	case *starlark.Dict:
-		result := make(map[string]any, val.Len())
-		for _, item := range val.Items() {
-			if k, ok := item[0].(starlark.String); ok {
-				result[string(k)] = starlarkToGo(item[1])
-			}
-		}
-		return result
-	default:
-		return v.String()
-	}
-}
-
 // verifyHMAC checks the HMAC-SHA256 signature of a webhook payload.
 func verifyHMAC(body []byte, secret, signature string) bool {
 	if signature == "" {