Akhil/optimise nosql - #214

Implements the bulk delete confirmation dialog for the multiselect collections feature:
- Added onDeleteMultiple prop to component interface
- Added bulk delete dialog that displays selected collections before deletion
- Dialog shows collection names in a scrollable list with trash icons
- Cancel button closes dialog without action
- Delete button calls onDeleteMultiple callback and clears selection
- Uses existing i18n translations with fallback defaults

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

…e API

Add deleteMultipleCollections method to useCollections hook and wire handler in api-client.tsx to support batch deletion of API collections.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Fixes race condition where delete dialog would close before API calls completed.
Added isDeleting loading state to prevent multiple simultaneous deletions and
updated button text to show deletion progress.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

…al failure support

Replace Promise.all with Promise.allSettled to gracefully handle partial failures where
some collections delete successfully while others fail. Now provides:

- Partial failure handling: Remove successfully deleted collections from state even if
  others fail, preventing inconsistent UI state
- Better error messaging: Toast shows how many succeeded/failed with list of failed
  collection names for transparency
- Dialog stays open on failure: Allows user to retry instead of losing context
- Detailed logging: Tracks both successful and failed IDs for debugging
- Re-throws errors: Caller (dialog) knows deletion failed and can handle accordingly

This ensures the UI stays in a consistent state and users aren't left wondering what
happened when a batch operation partially succeeds.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>