Fix tool results visibility, dynamic system prompt, rebrand Galaxy AI to Galaxy

- Rewrite extract_system_prompt to dynamically include CWD, OS, shell, git,
  project rules, and tool usage guidance from request context
- Fix extract_tool_result_content and format_tool_call_result to properly
  handle Grep, FileGlobV2, and ApplyFileDiffs results (were returning empty
  'Tool completed successfully' strings - model never saw file lists)
- Rename all 'Galaxy AI' references to just 'Galaxy' (menu, window title,
  bundle names, plist, welcome text, about)
- Update smoke test with file visibility test prompt
- Suppress dead_code warnings on unused smoke test functions

app/src/uri/browser_url_handler.rs

@@ -1,6 +1,6 @@
 use url::Url;
 
-const DEFAULT_TITLE: &str = "Galaxy AI";
+const DEFAULT_TITLE: &str = "Galaxy";
 const BASE_APP_PATH: &str = "/app";
 
 pub fn update_browser_url(url: Option<Url>, force_redirect: bool) {