feat(browser): search suggestion in address bar dropdown

[Jinwoo-H]

Summary

• Show a "query — Google Search" suggestion at the top of the address bar dropdown when input looks like a search query (like Chrome/Firefox omnibox)
• For URL-like inputs (e.g. "github.com"), the search suggestion appears last as a fallback
• Search icon distinguishes search suggestions from history entries
• Uses the styled Select component for the search engine settings dropdown (replaces native <select>)

Test plan

• Type a search query (e.g. "test") in address bar → first suggestion should be "test — Google Search"
• Press Enter without arrow-keying → should navigate to Google search
• Type a URL-like input (e.g. "github.com") → history suggestions first, search option last
• Arrow down through suggestions → search suggestion has magnifying glass icon, history has globe
• Change search engine in settings → suggestion label updates (e.g. "test — DuckDuckGo Search")