feat: Add rebrand CI/CD workflows to main branch

- Add 72 rebrand workflow files (polkadot→pezkuwi, substrate→bizinikiwi, cumulus→pezcumulus)
- Add GitHub actions, issue templates, and configs
- Removed unnecessary workflows (fork-sync, gitspiegel, upstream-tracker, sync-templates, backport)
- Renamed zombienet test files to match new naming convention

.github/actions/workflow-stopper/action.yml

@@ -0,0 +1,28 @@
+name: "stop all workflows"
+description: "Action stops all workflows in a PR to save compute resources."
+inputs:
+  app-id:
+    description: "App id"
+    required: true
+  app-key:
+    description: "App token"
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Worfklow stopper - Generate token
+      uses: actions/create-github-app-token@d72941d797fd3113feb6b93fd0dec494b13a2547 # v1.12.0
+      id: app-token
+      with:
+        app-id: ${{ inputs.app-id }}
+        private-key: ${{ inputs.app-key }}
+        owner: "pezkuwichain"
+        repositories: "workflow-stopper"
+    - name: Workflow stopper - Stop all workflows
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/pezkuwichain/workflow-stopper/actions/workflows/stopper.yml/dispatches
+        ref: main
+        inputs: '${{ format(''{{ "github_sha": "{0}", "github_repository": "{1}", "github_ref_name": "{2}", "github_workflow_id": "{3}", "github_job_name": "{4}" }}'', github.event.pull_request.head.sha, github.repository, github.ref_name, github.run_id, github.job) }}'
+      env:
+        GITHUB_TOKEN: ${{ steps.app-token.outputs.token }}