[META] Back-end Kanban issue tracker

I don't think individual small bugfixes are worth mentioning here. This meta issue is about the big picture.

Distinguish between "API" (as in, for the UI) and config management. They are interdependent though.

This should keep y'all busy while I'm on vacation. 😄 See you all on Friday, July 5! 👋

#3455942: HTTP API: update /xb-components to use Component config entity's default values is unblocked because #3452397: Allow specifying default props values when opting an SDC in for XB landed.

Next/new issue on the config management side of things: #3460232: [PP-1] Support XB config entities with component trees that reference File/Media, use target_uuid and embed — aka: self-contained content entity dependencies.

Big update — lots of things have landed Thu/Fri/today 😊

1. #3455898: Connect client & server, with zero changes to client (UI): rough working endpoints that mimic the UI's mocks landed ~3 weeks ago (the day after I went on vacation). That in turn unblocked #3452512: Add component instance edit form to contextual panel (which landed earlier today), and now the next step is unblocked: #3461422: Evolve component instance edit form to become simpler: generate a Field Widget directly.
2. #3453152: Centralize & standardize logic for constructing *PropSource objects + kernel test coverage landed. Next on the "prop source" front: docs → #3461490: Document the current JSON-based data model, and describe in an ADR — I'm on that.
3. #3455728: FieldType: Support storing component *trees* instead of *lists* landed. Next on that front: #3456024: Lift most logic out of ComponentTreeItem::preSave() and into a new validation constraint. @tedbow is already on that.
4. #3452397: Allow specifying default props values when opting an SDC in for XB landed. Next on that front:
   1. #3455942: HTTP API: update /xb-components to use Component config entity's default values (already ready for review)
   2. #3460232: [PP-1] Support XB config entities with component trees that reference File/Media, use target_uuid and embed — aka: self-contained content entity dependencies — @f.mazeikis will begin that in the next few days.
   3. #3461499: Support complex SDC prop shapes: introduce (Storable)PropShape to compute field type storage settings

With the shift in direction that happened after #3461499-13: Support complex SDC prop shapes: introduce (Storable)PropShape to compute field type storage settings, after discussing all that in detail with @lauriii, this meta issue needs a serious overhaul. See #3461499-17: Support complex SDC prop shapes: introduce (Storable)PropShape to compute field type storage settings for notes of that meeting.

I won't have time to get that overhaul done today. Will work on that tomorrow.

I've failed to keep this meta up-to-date since mid-July.

We're understaffed on the coordination side and have hence been unable to convey the "next steps" fully tracked in this issue. In practice, this has turned out to be impossible, because there's neither comprehensive designs nor comprehensive technical implementation plans: we've been at best been able to plan a few weeks ahead, and we've constantly had to readjust.
That's why along the way, we've been using #3454094: Milestone 0.1.0: Experience Builder Demo to keep the team laser-focused on the next highest priority per Product Lead @lauriii, who's been keeping that list up-to-date 😊

That's what's been informing what blockers to tackle to keep working towards reducing that list to zero.

Hopefully we'll eventually be able to plan further ahead.

These have not been used in ages. See #3515932: Milestone 1.0.0-beta1: Enable creation of non-throwaway sites.