rename(547): the repo is FabledGrimoire, and no stray "scribe" is left

The forge repo is now bvandeusen/FabledGrimoire. The plugin marketplace default,
the install commands in the docs and plugin README, the CI requirements title and
the example repo URLs in comments and tests follow it. docs/development.md now
names the image the build actually publishes, fabledgrimoire.

Two test names still said "scribes_own"; they now say "grimoires_own".

What still says scribe does so on purpose:
- the backup reader's accepted archive names and prefix;
- the label every stored secret is sealed under;
- the notes on keeping an old install's database names;
- the old migrations.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/grimoire/models/repo_binding.py

@@ -9,7 +9,7 @@ class RepoBinding(Base, TimestampMixin):
     """Maps a git repository to the Grimoire project it represents.
 
     The SessionStart hook sends the working repo's normalized remote
-    (`repo_key`, e.g. ``git.fabledsword.com/bvandeusen/fabledscribe``) and the
+    (`repo_key`, e.g. ``git.fabledsword.com/bvandeusen/fabledgrimoire``) and the
     server resolves it to a project — so the operator can work across many
     repos/projects without pinning a project id in plugin config. The key is a
     *stable identifier* (the git remote), not a dir-name heuristic.