wip: simplify wisp architecture - single db with Wisp flag (bd-bkul)

Progress on eliminating separate .beads-wisp/ directory:

- Add --wisp flag to bd create (creates issue with Wisp=true)
- Update bd wisp create to use main db instead of separate wisp storage
- Update bd wisp list to query main db with Wisp filter
- Update bd wisp gc to work with main database
- Add Wisp field to RPC ListArgs for daemon mode support
- Fix terminology: use "old/abandoned" for time-based cleanup,
  reserve "stale" for graph-pressure staleness (per Gas Town taxonomy)

Still TODO:
- Finish mol squash simplification (remove cross-store logic)
- Remove runWispSquash and squashWispToPermanent functions
- Update mol burn similarly
- Deprecate .beads-wisp/ functions in internal/beads/beads.go
- Test all changes

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

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

internal/rpc/server_issues_epics.go

@@ -821,6 +821,9 @@ func (s *Server) handleList(req *Request) Response {
 		filter.ParentID = &listArgs.ParentID
 	}
 
+	// Wisp filtering (bd-bkul)
+	filter.Wisp = listArgs.Wisp
+
 	// Guard against excessive ID lists to avoid SQLite parameter limits
 	const maxIDs = 1000
 	if len(filter.IDs) > maxIDs {