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>

tests/test_moment_delivery.py

@@ -292,7 +292,7 @@ def test_the_hook_and_the_routes_agree_on_every_name():
         assert name in route
 
 
-def test_the_hook_leaves_scribes_own_tools_to_their_responses():
+def test_the_hook_leaves_grimoires_own_tools_to_their_responses():
     assert "mcp__*grimoire*__*) exit 0" in HOOK.read_text()