fix: resolve 3 protocol bugs, improve CLI and snapshot code quality (#487)

## Summary

- Fix `allowFileAccess` being silently stripped from launch commands by adding it to the Zod schema in `protocol.ts` (the `--allow-file-access` CLI flag was not reaching the browser)
- Fix `trace stop` requiring a path argument despite help text documenting it as optional -- now works with or without a path
- Fix `addscript`/`addstyle` silently succeeding when neither `content` nor `url` is provided -- now returns a validation error
- Replace hardcoded ANSI escape code with `color::error_indicator()` in `main.rs` to respect `NO_COLOR`
- Fix double-parse pattern and add descriptive expect messages in `commands.rs`
- Fix incomplete string escaping in `snapshot.ts` `buildSelector` (use `JSON.stringify` instead of manual quote escaping)
- Simplify redundant ternary in `snapshot.ts` cursor-interactive role assignment
- Sync docs changelog with CHANGELOG.md (v0.8.1 through v0.10.0)

cli/src/main.rs

@@ -470,7 +470,7 @@ fn main() {
             if flags.json {
                 println!(r#"{{"success":false,"error":"{}"}}"#, msg);
             } else {
-                eprintln!("\x1b[31m✗\x1b[0m {}", msg);
+                eprintln!("{} {}", color::error_indicator(), msg);
             }
             exit(1);
         }