fix(db): make Blogs.BlogId the only blog ID and drop BlogNames

Blogs.BlogId was a one-time copy of BlogNames and nothing kept it
current: 12,238 blogs first seen after 2026-08-07 had a BlogNames ID
but a NULL Blogs.BlogId, so GetBlogs' join on BlogId silently skipped
them and their 23,148 notes.

- retire-blognames.sql: stub Blogs rows for the 17 unregistered note
  participants, backfill IDs (none renumbered), make ix_Blogs_BlogId
  UNIQUE, drop BlogNames, and add triggers that stop a Blogs row with
  a BlogId from being deleted, renamed or renumbered
- AddNote registers both blogs via RegisterBlog (Blogs row + MAX+1 ID)
  and every query resolves names through Blogs instead of BlogNames
- verify-db-schema.sql reports a DB that still has BlogNames (1e)
- Update TL.db.md, AGENTS.md and the DB Browser saved queries

Co-Authored-By: Claude Opus 5.5 <[email protected]>

TL.sqbpro

@@ -15,9 +15,9 @@ ORDER BY
 FROM
 	Notes N
 	inner JOIN
-	BlogNames rbn on rbn.BlogId = N.RootBlogId
+	Blogs rbn on rbn.BlogId = N.RootBlogId
 	inner JOIN
-	BlogNames nbn on nbn.BlogId = N.NoteBlogId
+	Blogs nbn on nbn.BlogId = N.NoteBlogId
 	inner JOIN
 	NoteTypes t on t.TypeId = N.TypeId
 	inner JOIN