fix: separate analyses dir so caching works with read-only recordings mount

The Docker web container mounts ./recordings as :ro, causing every cache
write to fail silently (PermissionError swallowed by bare except).

Fix: add --analyses-dir flag (default: <recordings>/analyses for local runs).
docker-compose.yml adds ./analyses:/analyses (writable) and passes
--analyses-dir /analyses to web.py. Cache write failures now print a
warning instead of being swallowed silently.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -16,7 +16,8 @@ services:
     build: .
     volumes:
       - ./recordings:/recordings:ro
+      - ./analyses:/analyses
     ports:
       - "8080:8080"
     restart: unless-stopped
-    command: ["python", "web.py", "--dir", "/recordings"]
+    command: ["python", "web.py", "--dir", "/recordings", "--analyses-dir", "/analyses"]