Feat v0.9.6 deprecate stage_type, collapse stage_mode

stage_type no longer validated — starlark_hook presence determines
automation. stage_mode collapsed from 4→3 values (form/delegated/
automated); "review" mapped to "form" on input for backward compat.
Migration 018 converts existing rows. Review surface removed (~110
lines). 4 package manifests updated.

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

server/models/workflow.go

@@ -56,9 +56,9 @@ type WorkflowStage struct {
 	Name             string          `json:"name"`
 	AssignmentTeamID *string         `json:"assignment_team_id,omitempty"`
 	FormTemplate     json.RawMessage `json:"form_template"`
-	StageMode        string          `json:"stage_mode"`  // form | review | delegated | automated
+	StageMode        string          `json:"stage_mode"`  // form | delegated | automated
 	Audience         string          `json:"audience"`    // team | public | system
-	StageType        string          `json:"stage_type"`  // simple | dynamic | automated
+	StageType        string          `json:"stage_type"`  // deprecated — retained for backward compatibility
 	AutoTransition   bool            `json:"auto_transition"`
 	StageConfig      json.RawMessage `json:"stage_config"`
 	BranchRules      json.RawMessage `json:"branch_rules"`
@@ -72,7 +72,6 @@ type WorkflowStage struct {
 
 const (
 	StageModeForm      = "form"
-	StageModeReview    = "review"
 	StageModeDelegated = "delegated"
 	StageModeAutomated = "automated"
 )
@@ -80,12 +79,22 @@ const (
 // ValidStageModes is the set of valid stage_mode values.
 var ValidStageModes = map[string]bool{
 	StageModeForm:      true,
-	StageModeReview:    true,
 	StageModeDelegated: true,
 	StageModeAutomated: true,
 }
 
-// ── Stage Type Constants ────────────────────
+// NormalizeStageModeInput maps deprecated stage_mode values to their
+// replacements. "review" → "form"; all others pass through unchanged.
+func NormalizeStageModeInput(mode string) string {
+	if mode == "review" {
+		return StageModeForm
+	}
+	return mode
+}
+
+// ── Stage Type Constants (deprecated) ───────
+// stage_type is redundant with starlark_hook presence and is no longer
+// validated. Constants are retained for backward-compatible references.
 
 const (
 	StageTypeSimple    = "simple"
@@ -93,13 +102,6 @@ const (
 	StageTypeAutomated = "automated"
 )
 
-// ValidStageTypes is the set of valid stage_type values.
-var ValidStageTypes = map[string]bool{
-	StageTypeSimple:    true,
-	StageTypeDynamic:   true,
-	StageTypeAutomated: true,
-}
-
 // ── Audience Constants ──────────────────────
 
 const (