Hide inactive boards, keep source and target stack apart, make the interval configurable

- Boards: BoardService::getUserBoards() defaults to $includeArchived = true,
  and that flag also gates the `deleted_at = 0` condition, so archived and
  trashed boards showed up in the dropdown. Request the filtered query
  instead, with a fallback to the no-arg call if the signature ever changes.
  Stacks need nothing: StackMapper::findAll() always filters deleted_at.
- Each stack dropdown now hides whatever the other one holds, so source and
  target can no longer be set to the same stack. The save-time check stays
  as the backstop for rows stored before this rule.
- RunWorkflowsJob reads its interval from config.php
  ('workflow_deck_automation.interval', seconds, default 300, clamped to a
  60s minimum). TimedJob re-reads the interval on every cron pass, so a
  changed value takes effect without any occ command.

CLAUDE.md

@@ -18,6 +18,10 @@ Deck's ACL/permission checks read the *live* `IUserSession`, not a value frozen
 
 The filter-matching logic (`WorkflowRunner::cardMatchesFilters()`, `::isOverdue()`) is deliberately `static` and side-effect-free so it's unit-testable without a real Deck installation — see `tests/Unit/Service/WorkflowRunnerFilterTest.php`.
 
+## Job interval comes from config.php
+
+`RunWorkflowsJob` reads `workflow_deck_automation.interval` (seconds, default 300, clamped to a 60s minimum) via `IConfig::getSystemValueInt()` in its constructor. That works *because* `TimedJob` re-reads `$this->interval` on every cron pass from the freshly constructed job — so editing `config.php` takes effect immediately, with no `occ` command and no re-registration. Don't move this into `appinfo/info.xml` or a stored app config; the constants (`INTERVAL_CONFIG_KEY`, `DEFAULT_INTERVAL`, `MINIMUM_INTERVAL`) on the job are the single source of truth and are referenced from the README.
+
 ## Registration is declarative, not Bootstrap-based
 
 Background jobs and classic personal settings are registered in `appinfo/info.xml` (`<background-jobs>`, `<settings><personal>/<personal-section>`), **not** via `IRegistrationContext` in `lib/AppInfo/Application.php` — that interface has no `registerBackgroundJob()`/`registerSettings()` methods on NC 34. `Application.php` is intentionally near-empty.
@@ -112,7 +116,9 @@ This app is on `@nextcloud/vue` ^9 / Vue 3. The v8 (Vue 2) prop spellings that m
 
 Deck's `RelationalEntity` swaps resolved relations for an `OCA\Deck\Db\RelationalObject` once an entity is enriched. So on an enriched board/card, `$acl->getParticipant()`, `$board->getOwner()` and a card assignment's participant return a `RelationalObject` (wrapping `OCA\Deck\Db\User`/`Group`/`Circle`), **not** a uid — the uid is its `getPrimaryKey()`. Probing for `getUID()` on the returned object finds nothing and yields `null`, which is how the settings UI's user dropdown came up empty *and* why the runner's assigned-user filter could never match. `DeckIntegrationService::unwrapUid()` handles both shapes (bare string and `RelationalObject`); route any new participant/owner field through it.
 
-Two more Deck facts that bit us in the same pass: a board's ACL does **not** contain its owner (a private board has an empty ACL, so participants must be seeded with `$board->getOwner()`), and ACL entries can be groups (`type === 1`) whose members have to be expanded via `IGroupManager`. `BoardService::getUserBoards()` merges own/group/circle boards and can return the same board twice, and it includes archived and trashed boards — `listBoardsForCurrentUser()` dedupes by id and drops those.
+Two more Deck facts that bit us in the same pass: a board's ACL does **not** contain its owner (a private board has an empty ACL, so participants must be seeded with `$board->getOwner()`), and ACL entries can be groups (`type === 1`) whose members have to be expanded via `IGroupManager`.
+
+**`BoardService::getUserBoards()` defaults to `$includeArchived = true`, and that flag also gates the `deleted_at = 0` condition** — with the default you get archived *and* trashed boards back. We call `getUserBoards(null, false)` (with a fallback to the no-arg form if Deck ever changes the signature) and still dedupe by id afterwards, because it merges own/group/circle boards and can return the same board twice. Stacks need no such handling: `StackMapper::findAll()` filters `deleted_at = 0` unconditionally and stacks have no archived state.
 
 ## Local-only notes