Release v1.0.3 - Add zip file creation to release process

- Update /release command to create zip files in releases/ folder
- Add v1.0.3 zip files for both Chrome and Firefox extensions

Files modified:
- .claude/commands/release.md
- releases/plebeian-signer-chrome-v1.0.3.zip (new)
- releases/plebeian-signer-firefox-v1.0.3.zip (new)

🤖 Generated with [Claude Code](https://claude.ai/code)

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

projects/chrome/public/manifest.json

@@ -2,7 +2,7 @@
   "manifest_version": 3,
   "name": "Plebeian Signer - Nostr Identity Manager & Signer",
   "description": "Manage and switch between multiple identities while interacting with Nostr apps",
-  "version": "1.0.2",
+  "version": "1.0.3",
   "homepage_url": "https://git.mleku.dev/mleku/plebeian-signer",
   "options_page": "options.html",
   "permissions": [