phsl / new-api

🧠 fix(Playground): Enhance <think> tag processing and remove redundant comments

This commit significantly refactors the handling of <think> tags within the Playground component to improve robustness, prevent Markdown rendering errors, and ensure accurate separation of reasoning and displayable content.

Key changes include:
- Modified `handleNonStreamRequest`, `onStopGenerator`, and `renderCustomChatContent` for more resilient <think> tag parsing.
- Implemented logic to correctly extract content from fully paired `<think>...</think>` tags.
- Added handling for unclosed `<think>` tags, particularly relevant during streaming responses, to capture ongoing thought processes.
- Ensured `reasoningContent` is accurately populated from all sources (API, paired tags, and unclosed streaming tags).
- Thoroughly sanitized the final `currentDisplayableFinalContent` to remove all residual `<think>` and `</think>` string instances, preventing issues with the Markdown renderer.
- Corrected the usage of `thinkTagRegex.lastIndex = 0;` to ensure proper regex state resetting before each use in loops.

Additionally, numerous explanatory comments detailing the "how" of the code (rather than the "why") have been removed to improve code readability and reduce noise.