Remove app:register CLI command, registerNpmPackage mutation, and GitHub Action

Auto-discovery via the marketplace catalog sync cron makes manual registration
unnecessary. Replace the publish-twenty-app composite action with inline CI
steps in the scaffolded workflow template. Consolidate unmerged migrations and
clean up dead code (fetchPackument, upsertFromNpmRegistration).

Made-with: Cursor

.github/actions/publish-twenty-app/action.yaml

@@ -1,37 +0,0 @@
-name: Publish Twenty App
-description: Build and publish a Twenty app to npm with provenance
-
-inputs:
-  npm-token:
-    description: npm token with publish permissions
-    required: true
-  npm-tag:
-    description: npm dist-tag
-    required: false
-    default: latest
-  app-path:
-    description: Path to the app directory
-    required: false
-    default: '.'
-
-runs:
-  using: composite
-  steps:
-    - uses: actions/setup-node@v4
-      with:
-        node-version: '24'
-        registry-url: https://registry.npmjs.org
-
-    - name: Install and build
-      shell: bash
-      working-directory: ${{ inputs.app-path }}
-      run: |
-        yarn install --immutable
-        npx twenty app:build
-
-    - name: Publish with provenance
-      shell: bash
-      working-directory: ${{ inputs.app-path }}/.twenty/output
-      env:
-        NODE_AUTH_TOKEN: ${{ inputs.npm-token }}
-      run: npm publish --provenance --access public --tag ${{ inputs.npm-tag }}