Expose experimental analytics plan history and improve navigation (#45772)

## What changed

- Expose `analytics_plan_history` in the experimental features menu for previewing consumer five-hour and weekly allowance history in `/analytics`. Keep it disabled by default.
- Add `h` and `l` as left/right navigation aliases in analytics, preserving explicit bindings and honoring remapped or unbound arrows.
- Use terminal-aware footer key colors to keep analytics shortcuts readable on light backgrounds.

## Testing

Add navigation tests for arrow equivalence, custom bindings, modifiers, and key repeat. Extend light-background contrast assertions and update style snapshots. Add a snapshot for the plan history experimental feature entry.

GitOrigin-RevId: 310e64a43a7dd08c8a3fd1efed6985805f7dd580

codex-rs/features/src/lib.rs

@@ -911,7 +911,11 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::AnalyticsPlanHistory,
         key: "analytics_plan_history",
-        stage: Stage::UnderDevelopment,
+        stage: Stage::Experimental {
+            name: "Analytics plan history",
+            menu_description: "Preview five-hour and weekly allowance history for consumer accounts in /analytics.",
+            announcement: "",
+        },
         default_enabled: false,
     },
     FeatureSpec {