feat: add pour warning for vapor-phase formulas, improve help text, add doctor check

- Add Phase field to Formula type to indicate recommended instantiation phase
- Add warning in 'bd mol pour' when formula has phase="vapor"
- Improve pour/wisp help text with clear comparison of when to use each
- Add CheckPersistentMolIssues doctor check to detect mol- issues in JSONL
- Update beads-release.formula.json with phase="vapor"

This helps prevent accidental persistence of ephemeral workflow issues.

cmd/bd/template.go

@@ -31,6 +31,7 @@ type TemplateSubgraph struct {
 	Dependencies []*types.Dependency         // All dependencies within the subgraph
 	IssueMap     map[string]*types.Issue     // ID -> Issue for quick lookup
 	VarDefs      map[string]formula.VarDef   // Variable definitions from formula (for defaults)
+	Phase        string                      // Recommended phase: "liquid" (pour) or "vapor" (wisp)
 }
 
 // InstantiateResult holds the result of template instantiation