Add visibility toggle to API key fields

[teungdao]

Description

Add eye icon toggle to show/hide API keys in provider settings panels

Expected Behavior

• Eye icon appears next to all API key input fields
• Clicking icon toggles between visible/hidden states
• Icon changes between open/closed eye visuals

Affected Providers

Amazon Bedrock, Anthropic, Chutes, Claude Code, Deepseek, GCP Vertex, Glama, Gemini, Groq, Human Relay, LiteLLM, LM Studio, Mistral, Moonshot, Ollama, OpenAI, OpenAI Compatible, Requesty, Unbound, VS Code LM API, xAI (Grok)