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/workflows/issues-auto-add-teyrchain.yml

@@ -0,0 +1,30 @@
+# If there are new issues related to the async backing feature,
+# add it to the teyrchain team's board and set a custom "meta" field.
+
+name: Add selected issues to Teyrchain team board
+on:
+  issues:
+    types:
+      - labeled
+
+jobs:
+  add-teyrchain-issues:
+    if: github.event.label.name == 'T16-async_backing'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Generate token
+        id: generate_token
+        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2.1.0
+        with:
+          app_id: ${{ secrets.PROJECT_APP_ID }}
+          private_key: ${{ secrets.PROJECT_APP_KEY }}
+      - name: Sync issues
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ steps.generate_token.outputs.token }}
+          script: |
+            // TODO: Implement issue sync for pezkuwichain project board
+            // Original action was pezkuwichain/github-issue-sync
+            // Project: 119 (Teyrchain team board)
+            // Fields: meta = 'async backing'
+            console.log('Issue sync placeholder - configure for pezkuwichain project board');