feat: ROUNDTABLE_* env vars with FABLEDSCRYER_* fallback

Reads ROUNDTABLE_<NAME> first, falls back to FABLEDSCRYER_<NAME> so
existing deployments keep working through the rebrand transition.
Covers DATABASE_URL, DATABASE__URL, SECRET_KEY, PLUGIN_DIR, CONFIG.

roundtable/migrations/env.py

@@ -16,18 +16,20 @@ target_metadata = Base.metadata
 
 def get_url() -> str:
     import os, yaml
-    cfg_path = os.environ.get("FABLEDSCRYER_CONFIG", "config.yaml")
+
+    def _env(suffix: str) -> str | None:
+        return os.environ.get(f"ROUNDTABLE_{suffix}") or os.environ.get(
+            f"FABLEDSCRYER_{suffix}"
+        )
+
+    cfg_path = _env("CONFIG") or "config.yaml"
     try:
         with open(cfg_path) as f:
             cfg = yaml.safe_load(f) or {}
         url = cfg.get("database", {}).get("url", "")
     except FileNotFoundError:
         url = ""
-    return (
-        os.environ.get("FABLEDSCRYER_DATABASE_URL")
-        or os.environ.get("FABLEDSCRYER_DATABASE__URL")
-        or url
-    )
+    return _env("DATABASE_URL") or _env("DATABASE__URL") or url
 
 
 def _resolved_url() -> str: