feat(category): faster removal

[nijel]

Collect components to be removed to better handle situations with many linked components being removed.

[Copilot]

Pull request overview

This PR improves the performance of category removal by batching post-delete side effects (stats recalculation and linked-component alert refresh) and by avoiding work for components that are also being removed, which is especially important when a category contains many linked components.

Changes:

• Introduces RemovalBatch to deduplicate and defer stats updates + linked component update_alerts() until transaction commit.
• Refactors component/category removal tasks to support batched removals and skip propagation updates for components being removed.
• Adds regression tests around batching behavior and documents the user-visible improvement in the changelog.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
weblate/trans/tasks.py	Refactors removal flow into helper functions and adds batched category removal with deferred flush.
weblate/trans/removal.py	Adds RemovalBatch helper to collect and flush deduped updates on commit.
weblate/trans/models/component.py	Adds in-memory removal_batch attribute on Component instances used during deletion.
weblate/trans/models/__init__.py	Updates component deletion signals to batch stats/linked-alert updates when removal_batch is set.
weblate/trans/tests/test_categories.py	Adds tests verifying batching of linked alert refresh, skipping propagation, and batched stats updates.
docs/changes.rst	Adds changelog entry for faster category removal.

[Copilot]

Pull request overview

This PR improves the performance of category removal in Weblate by batching follow-up work (stats updates and linked-component alert refreshes) so large removals—especially with many linked components—do not trigger repetitive per-component updates.

Changes:

• Add RemovalBatch + contextvar plumbing to collect removed component IDs, parent stats objects, and linked-component alert refresh targets.
• Refactor category_removal (and component removal internals) to use the batch, flush once on transaction commit, and skip propagation work for components that will be removed.
• Add regression tests validating batching behavior and update/propagation skipping; document the change in the changelog.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
weblate/trans/tasks.py	Refactors category removal to pre-collect removal targets and use a single batched flush for stats/alerts, while avoiding propagation scheduling for soon-to-be-removed components.
weblate/trans/removal.py	Introduces RemovalBatch and a context manager for batched removal side-effects flushed on commit.
weblate/trans/models/init.py	Updates delete signals to use the active removal batch (instance-bound or contextvar) to collect stats and linked alert refreshes instead of scheduling per-delete callbacks.
weblate/trans/models/component.py	Adds a non-persistent removal_batch attribute to component instances to associate deletions with a batch.
weblate/trans/tests/test_categories.py	Adds tests covering batched alert refresh, propagation skipping, and batched parent stats updates during category removal.
docs/changes.rst	Adds a changelog entry for faster category removal.