Replace "Traits" Tag Input with a Standard Text Area for Better Usability

### Problem

The current "Traits" input field is implemented as a tag-based system that requires users to "type a trait and press Enter or Tab."

This design has two major flaws:

1. **Poor Usability:** It forces a tedious, one-by-one manual input process and prevents users from easily pasting or editing a comprehensive set of instructions.

2. **Violates User Expectation:** It goes against the established industry standard set by competitors like ChatGPT and Claude, where a simple, large text area is used for this purpose. Users intuitively expect to be able to paste a full paragraph.

### Proposed Solution

Replace the current tag-style input component with a standard, multi-line text area (`<textarea>`).

This component should function identically to the "Anything else..." field, allowing for easy pasting and editing of long-form text.

### Justification

As T3 Chat is positioned as a ChatGPT alternative, matching fundamental usability features is crucial. The current implementation is a significant point of friction that makes the customization process feel unintuitive and less powerful than it should be. This change would resolve the usability issue and align the product with user expectations. below is a screenshot from ChatGPT, and i could paste a quite long one

ignore the Chinese text, that is not related to the point