refactor: architecture cleanup across CLI and Rust layers

- Fix logger.warn calling log.info instead of log.warn
- Fix process.exit(0) to exit(1) on Rust install refusal
- Fix loose == to === in merge.ts
- Remove dead tray icon set-then-delete code and duplicate url_type assignment
- Remove orphaned code-review-graph.ts and stale @types/page-icon dep
- Clean up redundant DEFAULT_PAKE_OPTIONS import alias in cli-program.ts
- Move feature-appending into buildBaseCommand(), removing duplication from Mac/Win/Linux builders
- Reuse getSafeAppName in icon.ts instead of duplicating the expression
- Split 458-line mergeConfig() into 7 focused helpers
- Replace sync fs I/O with async in combine.ts
- Reduce tokio features from full to time (only time::sleep is used)
- Set codegen-units = 1 to complement lto = thin in release profile
- Replace 12+ .unwrap() in Rust event handlers with let _ = or unwrap_or
- Replace std::process::exit(0) with app.exit(0) for graceful tray quit
- Replace Shortcut::from_str().unwrap() with match to avoid startup panic
- Use ? instead of .unwrap() for set_system_tray/set_global_shortcut in setup