DEV-126: Move to Developer Platform + Clean up Backstage

[Copilot]

Transition repository ownership from engineering-services to developer-platform team and remove deprecated Backstage configuration.

Changes

• CODEOWNERS: Updated team from @BESTSELLER/engineering-services to @BESTSELLER/developer-platform
• policy.yml: Updated approval rules to require developer-platform team approval
• dependabot.yml: Removed engineering-services reviewer assignment
• catalog-info.yaml: Deleted Backstage catalog entity definition
• release-drafter.yml: Removed commented-out configuration lines

Note

Test failures are unrelated to this PR—they originate from PR #52's go-version library change affecting HashiCorp Vault's non-standard release tags (e.g., ent-changelog-1.15.9).

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/hashicorp/vault/releases
  • Triggering command: /tmp/go-build2198807500/b001/github-releasediff.test /tmp/go-build2198807500/b001/github-releasediff.test -test.testlogfile=/tmp/go-build2198807500/b001/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)