Host-crontab generation for `app.json` cron tasks now lives in the `cron` plugin, gated by a new `scheduler-uses-host-cron` trigger that the `docker-local` scheduler answers true while self-managed schedulers such as `k3s` answer false. This lets any host-cron scheduler participate in normal `app.json` cron without coupling to `scheduler-docker-local` or duplicating the crontab writer, while the `k3s` scheduler continues to manage its own in-cluster cron jobs.
Closes#8862.
Every Go-implemented plugin's `:report --format json` now emits keys without the redundant `<plugin>-` head segment, matching the shape bash plugins have always emitted. The CLI flag names and `:set` semantics are unchanged. For backwards compatibility during the 0.38.x patch series, the legacy `<plugin>-<property>` keys are emitted side-by-side with the new keys, and a future major release will drop the legacy keys. `common.ReportSingleApp` is refactored to accept a `ReportSingleAppInput` struct with a `Validate()` method so the input is checked before any work runs, which also catches the latent `"docker options"` reportType bug at the API boundary.
Adds the missing raw/global/computed report keys for ten settable properties across the ps, builder, scheduler, proxy, openresty, nginx, and scheduler-k3s plugins so external tooling can verify drift through `:report --format json`. The scheduler-k3s `token` is masked as `*******` in default stdout output and only unmasked when the report is requested via `--format json` or when the flag is queried explicitly by name; the same explicit-query unmasking rule is extended to the existing traefik `dns-provider-<env_var>` keys.
Renames the existing `## Internal properties` umbrella section to `## Properties` across all plugin docs and adds a new `### Settable properties` subsection enumerating every property accepted by each plugin's `:set` command. Each row lists scope, default, the actual `:report` flag shapes that surface the value, and a one-line description. The buildpacks plugin is included even though it uses `:set-property`, with a note in the subsection clarifying the legacy command name. Property lists, scopes, and report flags were verified against plugin source and the live dokku binary.
The `<plugin>-global-<property>` keys in `:report` output returned the resolved value with the built-in default substituted in, so external tooling could not distinguish a property that had been set globally to the default from one that had never been set. The bare keys for caddy, haproxy, and traefik global-only properties had the same shape. The `global-<property>` keys now hold the raw stored value and are empty when nothing has been set, and a new `computed-<property>` key holds the effective value used at runtime, falling back through the per-app value (where one exists), the global value, and the built-in default. The bare global-only keys for the three proxy plugins are removed in favor of the raw/computed pair. Closes#8631.
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.
