feat(plan-phase): suggest execute-phase when multiple plans created

Routes to batch execution when 2+ plans exist, with execute-plan
as alternative for interactive mode.

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

get-shit-done/workflows/plan-phase.md

@@ -523,24 +523,30 @@ Confirm: "Committed: docs(${PHASE}): create phase plan"
 
 <step name="offer_next">
 ```
-Phase plan created: .planning/phases/XX-name/{phase}-01-PLAN.md
-[X] tasks defined.
+Phase {X} planned: {N} plan(s) created in .planning/phases/XX-name/
 
 ---
 
 ## Next Up
 
+[If 1 plan created:]
 **{phase}-01: [Plan Name]** - [objective summary]
 
 `/gsd:execute-plan .planning/phases/XX-name/{phase}-01-PLAN.md`
 
+[If 2+ plans created:]
+**Phase {X}: [Phase Name]** - {N} plans ready
+
+`/gsd:execute-phase {X}`
+
 <sub>`/clear` first - fresh context window</sub>
 
 ---
 
 **Also available:**
 - Review/adjust tasks before executing
-[If multiple plans: - View all plans: `ls .planning/phases/XX-name/*-PLAN.md`]
+[If 2+ plans: - `/gsd:execute-plan {phase}-01-PLAN.md` - run plans one at a time interactively]
+[If 2+ plans: - View all plans: `ls .planning/phases/XX-name/*-PLAN.md`]
 
 ---
 ```