feat: Add proto prefix for distilled molecules (bd-hobo)

Distilled protos (via `bd mol distill`) now get bd-proto-xxx IDs.

Summary of distinct prefixes:
- bd-proto-xxx: templates created via distill
- bd-mol-xxx: instances created via pour
- bd-wisp-xxx: ephemeral instances via wisp create
- bd-xxx: regular issues

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

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

cmd/bd/mol_distill.go

@@ -256,6 +256,7 @@ func distillMolecule(ctx context.Context, s storage.Storage, subgraph *MoleculeS
 				IssueType:          oldIssue.IssueType,
 				Labels:             labels,
 				EstimatedMinutes:   oldIssue.EstimatedMinutes,
+				IDPrefix:           "proto", // bd-hobo: distinct prefix for protos
 			}
 
 			if err := tx.CreateIssue(ctx, newIssue, actorName); err != nil {