fix: respect --headed false flag in CLI (#757)

When user explicitly sets --headed false, the CLI was ignoring this
flag because the launch condition only checked if flags.headed was
true. This meant that --headed false would not trigger a launch
command, and subsequent commands would auto-launch with default
headless=true.

The fix adds a cli_headed flag to track when the user explicitly
sets --headed (regardless of value), and includes this in the
launch condition check.

Fixes #743

cli/src/main.rs

@@ -496,6 +496,7 @@ fn main() {
             flags.cli_allow_file_access.then_some("--allow-file-access"),
             flags.cli_download_path.then_some("--download-path"),
             flags.cli_native.then_some("--native"),
+            flags.cli_headed.then_some("--headed"),
         ]
         .into_iter()
         .flatten()
@@ -723,6 +724,7 @@ fn main() {
 
     // Launch headed browser or configure browser options (without CDP or provider)
     if (flags.headed
+        || flags.cli_headed  // User explicitly set --headed (even if false)
         || flags.executable_path.is_some()
         || flags.profile.is_some()
         || flags.state.is_some()