Enhance SEO file generation to include all examples

Description

The current buildScripts/generateSeoFiles.mjs script generates a sitemap and llms.txt that cover the main application routes and the "learn" section. However, it omits the numerous examples available in the repository, which are a critical resource for users and for providing context to LLMs.

This epic is to enhance the script to automatically discover and include all relevant examples by scanning the apps/ and examples/ directories.

Acceptance Criteria

1. File-based Discovery: The script must recursively scan the apps/ and examples/ directories to find all index.html files, treating each as a discoverable example.
2. URL Generation: The path to each discovered index.html should be converted into a relative URL.
3. Sitemap Integration: All discovered example URLs must be included in the generated dist/sitemap.xml.
4. llms.txt Integration: All discovered example URLs must be included in the generated apps/portal/llms.txt. A descriptive name should be generated from the file path for each example.
5. Exclusions: The file-based discovery should not include examples from node_modules or other irrelevant directories.

Implementation Suggestions

1. Create collectExampleRoutes(): Create a new function within buildScripts/generateSeoFiles.mjs named collectExampleRoutes. This function will encapsulate the logic for finding all example routes.
2. Integrate into collectAllRoutes(): Modify the existing collectAllRoutes function to call collectExampleRoutes and merge its results with the top-level and content routes.
3. File Scanning: Use a glob pattern like {apps,examples}/**/index.html to find all example entry points. For each file found, create a route object.
4. Update getLlmsTxt: The getLlmsTxt function will need to be updated to handle the new example routes, possibly creating a new "Examples" section in the output.