feat(collection): batch set/clear dance level in multi-select (#409)

[ibanner56]

What & why

Closes part of #409 ("Ability to add tags en-masse").

Scope note (important): The issue's title asks for bulk tagging, but batch Add tags / Remove tags already ship in multi-select (landed in #93, v0.1.0-beta.3) — as the issue owner's own triage comment confirms. The genuinely new ask is "add metadata/other info like level". This PR delivers that for level, reusing the existing batch-tag flow. rating / tunes / customFields are deferred to a follow-up issue to keep this atomic.

Changes

• Core DanceRepository.setLevelForMany(ids, {level, clearLevel, now}) — a single-transaction batched write that reuses the existing upsert path (keeping derived figure/FTS indexes consistent), skips unknown ids and dances already at the target level (idempotent), and returns the changed count. Running the whole batch in one transaction means an error leaves the collection untouched rather than half-updated. Stays Flutter-free.
• App new batch_level_dialog.dart single-choice picker (mirrors batch_tag_dialog.dart) with an explicit Unspecified (clear) option, using the repo's RadioGroup pattern.
• App dance_list_screen.dart: _batchSetLevel + _undoBatchLevel and a batch-set-level action in the selection app bar. Captures prior per-dance levels for a snackbar Undo, announces the result to assistive tech, and handles empty-selection / no-op cases.

Semantics

Setting a level is a replace (not additive like tags), so the picker is single-choice and the action is explicit + Undo-restorable. Idempotent (dances already at the target are skipped -> "No changes" when nothing changes). Non-selected dances are never touched. Empty selection disables the button and is a guarded no-op.

Tests & gates

• Core: dance_batch_level_test.dart — sets level on N ids in one txn; unknown ids ignored; empty list no-op; idempotent skip; clearLevel unsets and wins over a passed value; updatedAt stamped only on changed dances.
• App: batch_level_test.dart — applies to all selected; un-selected untouched; idempotent; clear path; Undo restores prior per-dance levels; no-op message; button disabled on empty selection.

Gates (exact):

• fvm dart format . — clean
• fvm flutter analyze — No issues found (0/0)
• core fvm dart test — 1804 passed, 4 skipped
• app fvm flutter test — 1651 passed

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

[Copilot]

Pull request overview

Adds a new Collection multi-select action to batch set or clear a dance’s difficulty level, implemented with a single-transaction core repository method and a new app dialog + undo flow.

Changes:

• Core: add DanceRepository.setLevelForMany(...) to update many dances’ level atomically and idempotently.
• App: add a batch level picker dialog with an explicit “Unspecified (clear)” option.
• App: wire a new selection-mode action to apply the batch change with snackbar + Undo, plus widget tests.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/compendium_core/lib/src/storage/repositories/dance_repository.dart	Adds batched repository API for setting/clearing level in one transaction.
packages/compendium_core/test/storage/dance_batch_level_test.dart	Adds core tests for batch set/clear/idempotency/unknown IDs.
app/lib/src/widgets/batch_level_dialog.dart	New single-choice batch level dialog with explicit clear option.
app/lib/src/screens/dance_list_screen.dart	Adds selection-mode “Set level” action with apply + undo + AT announcement.
app/test/screens/batch_level_test.dart	Adds widget tests covering apply/clear/idempotency/undo/disabled state.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.