feat(init): add IDE restart instruction after init

Add prominent restart instruction in success message to inform users
they need to restart their IDE/coding tool for slash commands to appear.
Applies to all tools when slash commands are created or refreshed.

Also updates cli-init spec to document the restart instruction requirement.

CHANGELOG.md

@@ -1,18 +1,5 @@
 # @fission-ai/openspec
 
-## 0.16.0
-
-### Minor Changes
-
-- c08fbc1: Add new AI tool integrations and enhancements:
-
-  - **feat(iflow-cli)**: Add iFlow-cli integration with slash command support and documentation
-  - **feat(init)**: Add IDE restart instruction after init to inform users about slash command availability
-    **feat(antigravity)**: Add Antigravity slash command support
-  - **fix**: Generate TOML commands for Qwen Code (fixes #293)
-  - Clarify scaffold proposal documentation and enhance proposal guidelines
-  - Update proposal guidelines to emphasize design-first approach before implementation
-
 ## Unreleased
 
 ### Minor Changes

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@fission-ai/openspec",
-  "version": "0.16.0",
+  "version": "0.15.0",
   "description": "AI-native system for spec-driven development",
   "keywords": [
     "openspec",