Enable batch export when only images are loaded (simple viewer mode)

[yulewu]

Currently, when only images are loaded (simple viewer mode, i.e., no cell table and masks), the batch export function is disabled. However, the batch export functionality already exists in the application.

Suggestion:

• Enable the batch export function when the user is in simple viewer mode (only images loaded, no cell table, no masks).
• Ensure any exported data adheres to the appropriate limitations/context of simple viewer mode.
• This will help users export multiple images without requiring cell table or masks data.

Benefits:

• Improves usability and flexibility for users who only want to export image data without the need for cell tables or masks.
• Streamlines workflows in simple viewer scenarios.

No major new implementation required, just revise logic to allow batch export in this mode.

[yulewu]

Update Summary: Simple viewer mode batch export (#78) (commit 8d7ae59)

Enabled BatchExportPlugin in simple viewer mode (when cell_table is None), allowing full-FOV and ROI exports to work without a cell table loaded.

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Actions Taken

• Whitelist expansion (display_ui()):
  Added "export_fovs" to the allow_plugins set used in simple viewer mode so BatchExportPlugin is instantiated even when no cell table is present.
• _refresh_mode_availability() added to BatchExportPlugin:
  New method checks whether main_viewer.cell_table is None. If so, the Single Cells tab content in mode_tabs is replaced with an informational HTML notice; when a cell table is set later, the original single_cell_box is restored. Also resets the active tab index away from Single Cells when no table is loaded.
• Wired into lifecycle hooks:
  _refresh_mode_availability() is called from __init__ (after refresh_overlay_capabilities()), on_cell_table_change(), and after_all_plugins_loaded().

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Files Changed

• ueler/viewer/ui_components.py — display_ui() simple-mode plugin whitelist now includes "export_fovs".
• ueler/viewer/plugin/export_fovs.py — Added _refresh_mode_availability() method and wired it into __init__, on_cell_table_change(), and after_all_plugins_loaded().
• tests/test_export_fovs_batch.py — Added TestSimpleViewerModeExport (9 tests) and no-op _refresh_mode_availability override in the existing stub to prevent mode_tabs attribute errors.

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Tests

python -m unittest tests.test_export_fovs_batch -v

• ✅ 17/18 tests passed (1 pre-existing failure in test_export_fovs_batch_writes_file, unrelated to this change)

[yulewu]

Problem: The marker set dropdown in batch export does not update when a new marker set is added or edited in the channel controls.

Requested fix: Refresh the batch export plugin's marker set dropdown whenever a new marker set is defined or edited. This allows users to select the newly created marker set for export without restarting the viewer or manually refreshing the plugin.

Action Required:

• Wire the batch export plugin to listen for marker set changes in the channel controls (likely via an observer or callback).
• Update the marker set Dropdown options dynamically when the registry changes.