refactor: rename Ephemeral → Wisp (Steam Engine metaphor)

Wisp = ephemeral vapor produced by the Steam Engine (Gas Town).
This aligns with the metaphor:
- Claude = Fire
- Claude Code = Steam
- Gas Town = Steam Engine
- Wisps = ephemeral vapor it produces

Changes:
- types.Issue.Ephemeral → types.Issue.Wisp
- types.IssueFilter.Ephemeral → types.IssueFilter.Wisp
- JSON field: "ephemeral" → "wisp"
- CLI flag: --ephemeral → --wisp (bd cleanup)
- All tests updated

Note: SQLite column remains "ephemeral" (no migration needed).
This is a breaking change for JSON consumers using 0.33.0.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/rpc/protocol.go

@@ -73,8 +73,8 @@ type CreateArgs struct {
 	Labels             []string `json:"labels,omitempty"`
 	Dependencies       []string `json:"dependencies,omitempty"`
 	// Messaging fields (bd-kwro)
-	Sender    string `json:"sender,omitempty"`     // Who sent this (for messages)
-	Ephemeral bool   `json:"ephemeral,omitempty"`  // Can be bulk-deleted when closed
+	Sender string `json:"sender,omitempty"` // Who sent this (for messages)
+	Wisp   bool   `json:"wisp,omitempty"`   // Wisp = ephemeral vapor from the Steam Engine; bulk-deleted when closed
 	RepliesTo string `json:"replies_to,omitempty"` // Issue ID for conversation threading
 }
 
@@ -96,8 +96,8 @@ type UpdateArgs struct {
 	RemoveLabels       []string `json:"remove_labels,omitempty"`
 	SetLabels          []string `json:"set_labels,omitempty"`
 	// Messaging fields (bd-kwro)
-	Sender    *string `json:"sender,omitempty"`     // Who sent this (for messages)
-	Ephemeral *bool   `json:"ephemeral,omitempty"`  // Can be bulk-deleted when closed
+	Sender *string `json:"sender,omitempty"` // Who sent this (for messages)
+	Wisp   *bool   `json:"wisp,omitempty"`   // Wisp = ephemeral vapor from the Steam Engine; bulk-deleted when closed
 	RepliesTo *string `json:"replies_to,omitempty"` // Issue ID for conversation threading
 	// Graph link fields (bd-fu83)
 	RelatesTo    *string `json:"relates_to,omitempty"`    // JSON array of related issue IDs

internal/rpc/server_issues_epics.go

@@ -81,8 +81,8 @@ func updatesFromArgs(a UpdateArgs) map[string]interface{} {
 	if a.Sender != nil {
 		u["sender"] = *a.Sender
 	}
-	if a.Ephemeral != nil {
-		u["ephemeral"] = *a.Ephemeral
+	if a.Wisp != nil {
+		u["wisp"] = *a.Wisp
 	}
 	if a.RepliesTo != nil {
 		u["replies_to"] = *a.RepliesTo
@@ -176,8 +176,8 @@ func (s *Server) handleCreate(req *Request) Response {
 		EstimatedMinutes:   createArgs.EstimatedMinutes,
 		Status:             types.StatusOpen,
 		// Messaging fields (bd-kwro)
-		Sender:    createArgs.Sender,
-		Ephemeral: createArgs.Ephemeral,
+		Sender: createArgs.Sender,
+		Wisp:   createArgs.Wisp,
 		// NOTE: RepliesTo now handled via replies-to dependency (Decision 004)
 	}