fix(copilot): add vscode_askquestions guidance and AskUserQuestion to plan-phase

Copilot agents use vscode_askquestions as the equivalent of AskUserQuestion.
Without explicit guidance they sometimes omit questioning steps that depend
on AskUserQuestion, causing extra billing and incomplete workflows.

- Add <runtime_note> to plan-phase, discuss-phase, execute-phase, and
  new-project commands mapping vscode_askquestions to AskUserQuestion
- Add AskUserQuestion to plan-phase allowed-tools (was missing, causing
  the planner orchestrator to skip user questions in some runtimes)

Closes #1476

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

commands/gsd/discuss-phase.md

@@ -34,6 +34,10 @@ Extract implementation decisions that downstream agents need — researcher and
 @~/.claude/get-shit-done/templates/context.md
 </execution_context>
 
+<runtime_note>
+**Copilot (VS Code):** Use `vscode_askquestions` wherever this workflow calls `AskUserQuestion`. They are equivalent — `vscode_askquestions` is the VS Code Copilot implementation of the same interactive question API.
+</runtime_note>
+
 <context>
 Phase number: $ARGUMENTS (required)
 

commands/gsd/execute-phase.md

@@ -35,6 +35,10 @@ Context budget: ~15% orchestrator, 100% fresh per subagent.
 @~/.claude/get-shit-done/references/ui-brand.md
 </execution_context>
 
+<runtime_note>
+**Copilot (VS Code):** Use `vscode_askquestions` wherever this workflow calls `AskUserQuestion`. They are equivalent — `vscode_askquestions` is the VS Code Copilot implementation of the same interactive question API.
+</runtime_note>
+
 <context>
 Phase: $ARGUMENTS
 

commands/gsd/plan-phase.md

@@ -10,6 +10,7 @@ allowed-tools:
   - Glob
   - Grep
   - Task
+  - AskUserQuestion
   - WebFetch
   - mcp__context7__*
 ---
@@ -26,6 +27,10 @@ Create executable phase prompts (PLAN.md files) for a roadmap phase with integra
 @~/.claude/get-shit-done/references/ui-brand.md
 </execution_context>
 
+<runtime_note>
+**Copilot (VS Code):** Use `vscode_askquestions` wherever this workflow calls `AskUserQuestion`. They are equivalent — `vscode_askquestions` is the VS Code Copilot implementation of the same interactive question API. Do not skip questioning steps because `AskUserQuestion` appears unavailable; use `vscode_askquestions` instead.
+</runtime_note>
+
 <context>
 Phase number: $ARGUMENTS (optional — auto-detects next unplanned phase if omitted)