[Content Migration] Migrate Blog to Nuxt Content

### Epic

4867

### Description

## Objective
Migrate the `/blog` section, including the blog index, pagination, and individual post pages, from 11ty to Nuxt.

## Tasks
- [ ] Build the `BlogIndex.vue` layout to display a list of recent articles with pagination.
- [ ] Build the `BlogPost.vue` layout for individual articles.
- [ ] Move all blog posts to the `content/blog/` directory.
- [ ] Map 11ty frontmatter (e.g., `date`, `author`, `tags`) to Nuxt Content queries to ensure chronological sorting works correctly.
- [ ] Generate a new RSS feed using Nuxt Nitro server routes to replace the 11ty feed.
- [ ] Delete the blog from the 11ty folder and remove the proxy rule for `/blog/**`.

## Acceptance Criteria
- The blog index correctly queries and lists markdown files chronologically.
- Individual posts render correctly.
- The RSS feed works and validates.
- 11ty no longer builds the blog.

### Acceptance Criteria

_No response_

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate

Start by tracing the current blog implementation in the 11ty folder and the proxy rule for `/blog/**`, then inspect the Nuxt entry points for `BlogIndex.vue`, `BlogPost.vue`, `content/blog/`, and Nitro server routes. Done means chronological index and post pages render, the RSS feed validates, and 11ty no longer builds the blog.

Written by the indexing model from the issue text.