v1.4.0 — DDEV-native mode

Repos that are not on Upsun can now use this add-on. Previously they could not start at all: the pre-start guard failed whenever config.platformsh.yaml was absent, fail_on_hook_fail made that fatal, and the recovery it printed died with no .platform.app.yaml.

Two modes, auto-detected, differing in which file is the source of truth:

	source of truth	ddev rdg-sync
derived — Upsun Fixed	.platform.app.yaml	regenerates config.platformsh.yaml; guard enforces freshness
native — everything else	.ddev/config.yaml, hand-written	nothing to derive, and says so

In native mode the guard stands aside, ddev rdg-sync is a no-op that explains which file to edit, and both upsun-*-pull commands refuse and point at ddev import-db. What a native repo gains is rdg/theme-watch.sh and corepack_enable; it declares the theme daemon itself.

The guard only goes inert when there is no app config and nothing generated — if config.platformsh.yaml exists the repo was derived once, so a missing app config is breakage, not a native project, and still fails.

Upgrading is a no-op for existing Upsun projects. Nothing about derived mode changed. Run ddev add-on get Rapid-Development-Group/ddev-rdg as usual — it must be the full add-on get, not a cherry-picked file, since the three commands now source the new rdg/mode.sh.

New: docs/dkr-to-ddev.md Part 3 — migrating a non-Upsun repo off dkr, with the compose-service → DDEV mapping.