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>

src/grimoire/rate_limit.py

@@ -0,0 +1,27 @@
+"""In-process sliding-window rate limiter.
+
+IMPORTANT — deployment note:
+  Rate limit counters are stored in memory and are lost on process restart.
+  When deployed behind a reverse proxy (nginx, Caddy, Traefik) you MUST set
+  TRUST_PROXY_HEADERS=true so that the real client IP is used as the bucket key
+  rather than the proxy's IP (which would cause all users to share one bucket).
+"""
+
+import asyncio
+import time
+from collections import defaultdict
+
+_buckets: dict[str, list[float]] = defaultdict(list)
+_lock = asyncio.Lock()
+
+
+async def is_rate_limited(key: str, max_requests: int, window_seconds: int) -> bool:
+    """Returns True if request should be blocked (limit exceeded)."""
+    async with _lock:
+        now = time.monotonic()
+        cutoff = now - window_seconds
+        _buckets[key] = [t for t in _buckets[key] if t > cutoff]
+        if len(_buckets[key]) >= max_requests:
+            return True
+        _buckets[key].append(now)
+        return False