HTTPRoute View: Effective Policy Stack

## Epic

Part of #526 - Customer PoC Analysis: Missing Features from CONNLINK-1058

## Context

From customer PoC analysis ([CONNLINK-1058](https://redhat.atlassian.net/browse/CONNLINK-1058)), add an Effective Policy Stack view to the HTTPRoute details page.

## Requirements

Add an Effective Policy Stack tab/section that displays:

- **Full resolution chain** showing each policy with:
- Policy scope (Route or Gateway)
- Resolution status: Default, Override, Enforced, or Overridden
- **Legend** explaining the resolution order:
- Gateway overrides → Route overrides → Route defaults → Gateway defaults

## Notes

- The policy stack may mix policies of different kinds - consider whether this makes sense for users or if policies should be grouped by type
- Resolution order should follow Gateway API policy attachment specification

Start at the HTTPRoute details page and review the Gateway API policy attachment specification for the required resolution order. Define the Effective Policy Stack tab or section, including policy scope, resolution status, and the legend; done means the full chain is displayed with the specified ordering and statuses.

Written by the indexing model from the issue text.