Summary

• Migrated OllamaAiService from IOllamaApiClient to Microsoft.Extensions.AI IChatClient (GA with .NET 10)
• Updated blog 6.1 to reflect MEA IChatClient usage and OllamaSharp 5.x implementation
• Added screenshots to all series-6 blogs; moved images to docs/screenshots/ (parent repo, not submodule)
• Renumbered series-6 articles: 6.4.1→6.5, 6.5→6.6, 6.6→6.7, 6.7→6.8 for consistent pairing of Angular/backend articles
• Swapped 6.6/6.7 so dotnet vector search follows angular vector search
• Updated SERIES-NAVIGATION-TOC.md with full series-6 listing
• Removed backward-compat ai-chat redirect from blog 6.3 and Angular source

Test plan

• Verify all series-6 blog images load correctly on GitHub
• Verify series navigation links in TOC resolve correctly
• Verify .NET API builds with MEA Abstractions 10.3.0