Retire worktree and voice feature flags (#54175)

## What changed

- Remove feature-flag checks from managed worktree creation and repository-aware session discovery, while retaining local workspace and trust checks.
- Make TUI voice availability follow platform support instead of `features.realtime_conversation`.
- Ignore `features.worktrees` and `features.realtime_conversation` configuration overrides, warn when managed requirements reference them, and hide both flags from `/experimental`, including catalogs from older servers.

## Testing

Add coverage for ignored configuration overrides and managed requirements, and update session filtering, worktree grouping, and experimental feature discovery tests for the retired flags.

GitOrigin-RevId: 1d64e890e6e2f8a78926a9ea163126c0890b068e

codex-rs/exec/src/lib.rs

@@ -421,11 +421,6 @@ pub async fn run_main(cli: Cli, arg0_paths: Arg0DispatchPaths) -> anyhow::Result
             .cloud_config_bundle(gate_cloud_config.clone())
             .build()
             .await?;
-        if !gate_config.features.enabled(Feature::Worktrees) {
-            anyhow::bail!(
-                "--worktree requires the worktrees feature; enable it with --enable worktrees"
-            );
-        }
         if let Some(ExecCommand::Fork(args)) = command.as_mut() {
             let saved_cwd = worktree::fork_source(
                 args,