feat: add automatic update check on session start

- Added check-updates script to package.json
- SessionStart hook fetches latest version from GitHub
- Compares local and remote versions
- Shows update notification when newer version available
- Works even after disconnecting from original repo
- Also improved release command documentation with clearer semver guidance

.claude/settings.json

@@ -7,6 +7,10 @@
           {
             "type": "command",
             "command": "[ -f FIRST_RUN ] && echo '{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"# 🚀 Welcome to Claudesidian!\\n\\n**This appears to be your first time using this vault.**\\n\\n## Quick Start\\n\\nRun the setup wizard:\\n\\n```\\n/init-bootstrap\\n```\\n\\n## What this will do:\\n\\n✅ Set up your personalized configuration\\n✅ Disconnect from the original repository  \\n✅ Help you import any existing Obsidian vault\\n✅ Configure your preferred workflow\\n✅ Create your PARA folder structure\\n\\nThe setup wizard will guide you through everything!\"}}' || true"
+          },
+          {
+            "type": "command",
+            "command": "npm run check-updates 2>/dev/null || true"
           }
         ]
       }