ci: remove GitHub CI — native git.hanzo.ai + cd.hanzo.ai only

This workflow ran on a self-hosted actions-runner-controller pool. ARC is
decommissioned: CI executes inside git.hanzo.ai (Gitea Actions, .hanzo/workflows)
and delivery is cd.hanzo.ai reconciling the reviewed image pin in
hanzoai/universe. GitHub is a mirror and runs nothing.

Removed rather than repointed — there is no GitHub-side pool to move to, and
leaving it would keep ARC load-bearing.

.github/workflows/initiate_release.yml

@@ -1,32 +0,0 @@
-# This workflow is agnostic to branches. Only maintain on develop branch.
-# To add/remove versions just modify the matrix.
-
-name: Create weekly release pull requests
-on:
-  schedule:
-    # 9:30 UTC => 3 PM IST Tuesday
-    - cron: "30 9 * * 2"
-  workflow_dispatch:
-
-jobs:
-  stable-release:
-    name: Release
-    runs-on: hanzo-build-linux-amd64
-    strategy:
-      fail-fast: false
-      matrix:
-        version: ["14", "15"]
-
-    steps:
-      - uses: octokit/[email protected]
-        with:
-          route: POST /repos/{owner}/{repo}/pulls
-          owner: frappe
-          repo: erpnext
-          title: |-
-            "chore: release v${{ matrix.version }}"
-          body: "Automated weekly release."
-          base: version-${{ matrix.version }}
-          head: version-${{ matrix.version }}-hotfix
-        env:
-          GITHUB_TOKEN: ${{ secrets.RELEASE_TOKEN }}