fix(ci): resolve release pipeline conflicts and clean repo structure

- Delete conflicting .releaserc.json (keep release.config.cjs as single source)
- Fix repo URL from Draculabo/AntigravityManager to evandrodevbr/GeminiNexus
- Fix @semantic-release/git to commit pnpm-lock.yaml (not package-lock.json)
- Normalize Node.js version to 20 across all workflows
- Add packageManager field to package.json for pnpm consistency
- Update AGENTS.md: npm -> pnpm (18 references)
- Update .gitignore: add tools/, thoughts/, binaries, one-shot scripts

.github/workflows/release.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 20
           cache: 'pnpm'
 
       - name: Install dependencies