refactor: rename package fabledassistant -> scribe (code-only)

Renames src/fabledassistant -> src/scribe and all imports, plus the
default DB name and DB user/password (fabled -> scribe) in config +
compose. 952 refs / 154 files. Reverses the old 'internal name stays
fabledassistant' convention.

Code-only: live databases are still physically named 'fabledassistant'.
Deployed environments must set POSTGRES_DB / POSTGRES_USER (or rename the
DB) since the defaults now resolve to 'scribe'. Repo (FabledScribe), git
host (fabledsword), MCP (fabled-git) and the image name (fabledscribe)
are intentionally unchanged.

ruff check src/ clean locally; CI (typecheck + pytest) is the gate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/scribe/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