Bug: `/speckit.specify` generates `spec.md` then immediately proceeds with implementation (creates `IMPLEMENTATION_REPORT.md`) in IntelliJ + Copilot

# Bug: `/speckit.specify` generates `spec.md` then immediately proceeds with implementation (creates `IMPLEMENTATION_REPORT.md`) in IntelliJ + Copilot

## Summary
Spec Kit’s documented workflow separates specification from implementation (`/speckit.specify` → `/speckit.plan` → `/speckit.tasks` → `/speckit.implement`). However, in IntelliJ IDEA with GitHub Copilot, running `/speckit.specify` generates `spec.md` and then immediately continues into implementation-like behavior without explicitly running `/speckit.implement`, eventually producing `IMPLEMENTATION_REPORT.md`.

## Environment
- IDE: IntelliJ IDEA 2025.3.1 (253.29346.138)
- Plugin: GitHub Copilot - Your AI Pair Programmer 1.5.62-241
- Model: Claude Sonnet 4.5
- Custom Instructions: None

- Spec Kit / Specify:
- CLI Version: 0.0.22
- Template Version: 0.0.90
- Template Released: 2025-12-04
- Python: 3.14.2

- OS:
- Platform: Darwin
- Architecture: arm64
- OS Version: Darwin Kernel Version 25.2.0 (xnu-12377.61.12~1/RELEASE_ARM64_T6000)

## Observed Context
- While observing this behavior, `constitution.md` was open in an editor tab/window in IntelliJ IDEA.

## Steps to Reproduce
1. Open a Spec Kit–initialized repository in IntelliJ IDEA.
2. Open GitHub Copilot Chat.
3. Run: `/speckit.specify `
4. Observe what happens after `spec.md` is generated.

## Expected Behavior
- `/speckit.specify` should generate/update the specification artifacts (e.g., `spec.md`) and stop at the specification phase.
- Implementation behavior (code edits / executing tasks) should only occur after explicitly running `/speckit.implement`.

## Actual Behavior
- `/speckit.specify` generates `spec.md`.
- Immediately afterward, Copilot continues as if implementing (code edits / implementation-level instructions) without running `/speckit.implement`.
- After the implementation-like work, `IMPLEMENTATION_REPORT.md` is created.

## Impact
- The step boundary between specification and implementation is not preserved, making it hard to keep the workflow predictable and reviewable.

## Requested Outcome
- Ensure `/speckit.specify` reliably stops after producing the specification artifacts and does not transition into implementation behavior unless `/speckit.implement` is explicitly executed.