LCFS - Screen Reader Does Not Read Entire Comment Log Filter Dropdown and Continues Reading Background Content

**Describe the Bug**
Within the Organisation Dashboard Comment Log tab, the screen reader does not properly read all options available within the Category filter dropdown. Additionally, when the dropdown is expanded, the screen reader continues reading content displayed behind the dropdown rather than remaining focused on the dropdown menu and its available options.

**Expected Behaviour**
When the Category dropdown is expanded, the screen reader should:
- Announce the dropdown control and its current state.
- Read all available dropdown options as the user navigates through them.
- Remain focused within the dropdown menu until the user exits or makes a selection.
- Prevent background page content from being read while navigating the active dropdown.

**Actual Behaviour**
The screen reader does not consistently read all dropdown options and instead continues reading comment log content located behind the expanded dropdown menu. Users are unable to reliably understand available filter options or navigate the dropdown independently.

**Implications**
Users who rely on screen readers may be unable to determine available filter values, understand their current selection, or successfully filter comment log results. Reading underlying page content while the dropdown is active creates confusion, disrupts navigation, and presents a significant accessibility barrier.

**Steps To Reproduce**
Steps to reproduce the behaviour:

User/Role: Organisation User using a Screen Reader

1. Go to the Organisation Dashboard.
2. Click on the "Comment log" tab.
3. Navigate to the Category filter dropdown using a keyboard and screen reader.
4. Expand the dropdown menu.
5. Use keyboard navigation to move through the available options.
6. Listen to the screen reader output.
7. Observe that not all dropdown options are announced and that the screen reader begins reading comment content displayed behind the dropdown.
8. Attempt to select a filter value using screen reader navigation.

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Start at the Organisation Dashboard's Comment Log tab and reproduce the Category filter dropdown issue with a keyboard and screen reader. Trace the dropdown's focus and option announcements, then verify that all options are readable, focus remains within the expanded dropdown, and background comment content is not announced.

Written by the indexing model from the issue text.