rename(547): the server is grimoire — package, image, DB defaults, backups

Step 2 of the Scribe -> Grimoire rename.

- src/scribe -> src/grimoire, and every import, patch target, module path,
  hypercorn entry point and `python -m grimoire.restore` with it; pyproject,
  uv.lock and the frontend package are named grimoire.
- Image git.fabledsword.com/bvandeusen/fabledgrimoire; CI's Postgres service
  runs as grimoire / grimoire_test.
- Compose files default the DB user, database and (prod) volume to grimoire,
  each overridable from .env, so an install created as Scribe keeps its data
  by setting POSTGRES_USER, POSTGRES_DB and PGDATA_VOLUME.
- Backups are written as grimoire-<ts>.tar with format grimoire-backup-tar.
  Archives named scribe-* with the scribe-backup-tar manifest still restore
  and are still counted at the destination (folder and S3), with tests.
- Exports, the MCP auth realm, the ASGI scope key and the persistent logger
  carry the new name.

Kept on purpose: the secret-sealing key label stays "scribe.secrets.v1",
because every stored secret was derived under it.

Plugin identity (plugin name, hooks, env vars, .scribe marker, skills) is
step 3.

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

tests/test_instruction_surfaces_agree.py

@@ -35,7 +35,7 @@ def _all_surfaces() -> list[tuple[str, str]]:
              for p in (ROOT / "plugin" / "skills").rglob("*.md")]
     found += [(str(p.relative_to(ROOT)), p.read_text())
               for p in (ROOT / "plugin" / "hooks").glob("*.md")]
-    server = ROOT / "src" / "scribe" / "mcp" / "server.py"
+    server = ROOT / "src" / "grimoire" / "mcp" / "server.py"
     found.append((str(server.relative_to(ROOT)), server.read_text()))
     return found
 
@@ -43,7 +43,7 @@ def _all_surfaces() -> list[tuple[str, str]]:
 def _instructions_text() -> str:
     """The _INSTRUCTIONS literal from server.py, as the client would see it."""
     import re
-    src = (ROOT / "src" / "scribe" / "mcp" / "server.py").read_text()
+    src = (ROOT / "src" / "grimoire" / "mcp" / "server.py").read_text()
     match = re.search(r'_INSTRUCTIONS = """(.*?)"""', src, re.S)
     assert match, "server.py no longer defines _INSTRUCTIONS as a triple-quoted literal"
     return match.group(1).strip()