The bats coverage for plugin :report keys has been uneven since the raw/global/computed split landed in PR #8640. This commit adds a single combined triplet test per settable property across app-json, builder, builder-dockerfile, builder-herokuish, builder-lambda, builder-nixpacks, builder-pack, builder-railpack, buildpacks, cron (maintenance), git (keep-git-dir, rev-env-var, source-image), logs (vector-sink, vector-global-image, vector-global-networks), network (attach-post-create, attach-post-deploy, initial-network), proxy (per-app type), ps (stop-timeout-seconds), registry (image-repo, push-on-release, push-extra-tags), storage (build/deploy/run mounts), and adds a new tests/unit/scheduler.bats and tests/unit/nginx-vhosts_properties.bats. Brings ps `procfile-path` and `stop-timeout-seconds` global getters in line with the #8640 convention (raw global, default resolved in computed). Documents the read-only and internal properties that surface in `:report` (or are written by Dokku) but cannot be managed by `:set` in a new `## Internal properties` section appended to each affected plugin's docs page.
Per-plugin management docs now describe the properties introduced by the env-var-to-property migration in PR #8498, and stale prose and command-output examples that still referenced the old `DOKKU_*` names have been refreshed. The deprecated env vars table moves out of `environment-variables.md` and into the 0.38.0 migration guide, where it functions as a one-time pointer for upgrading users rather than ongoing reference material.
