Frontend converted-value editor has no accessible name

#### Describe the bug After applying a converter in Chat, the editable converted-value textarea has no accessible name. The original textarea is announced as `Type prompt here`, but the converted field is exposed only as an unnamed `textbox`, so screen-reader users cannot identify which value they are reviewing or editing. The nearby `Converted` text is not a `` and is not associated through `aria-labelledby`. The textarea also has no `aria-label` or placeholder. This affects WCAG 2.1 success criteria 4.1.2 (Name, Role, Value) and 3.3.2 (Labels or Instructions). Tested source: [`ChatInputArea.tsx` lines 263-272](https://github.com/microsoft/PyRIT/blob/37bb7377ec3f8ed547b9a52f4536447c097e0f33/frontend/src/components/Chat/ChatInputArea.tsx#L263-L272). #### Steps/Code to Reproduce 1. Open a writable multi-turn chat and enter `hello`. 2. Open the converter panel. 3. Select **Base64Converter** and choose **Use Converted Value**. 4. Inspect the two textarea accessibility nodes. ```text - textbox "Type prompt here": hello - textbox: aGVsbG8= ``` #### Expected Results The converted-value field has a persistent visible and accessible name, such as `Converted prompt`. #### Actual Results The converted-value field is an unnamed editable `textbox`. Its visible `Converted` text is not programmatically associated with it. #### Screenshots N/A. The deterministic accessibility-tree output is included above. #### Versions - OS: Windows - Browser: Playwright Chromium (`@playwright/test` 1.62.1) - Python: 3.14.4 - PyRIT: `main` at `37bb7377ec3f8ed547b9a52f4536447c097e0f33`