Pi compatibility automation v1.0.0

Shared Pi release-compatibility automation for the 26-repository fleet: reusable GitHub Actions, independent official/fork host qualification, native Git/npm consumer checks, grouped Renovate configuration, scheduled canary reporting and the fork reverse-dependency contract.

The initial qualified baseline is official Pi 0.86.1 and the maintained fork. Windows results remain visible diagnostics under the explicit rollout waiver. Required non-Windows checks remain enforced; upstream Pi 0.87.0 enters through the new candidate-update flow.

Reusable workflow and preset source: fe049ea97a8c91d1a4c3a0958a85b37c7759dcc6.