fix: add device_fingerprint to PB schema + fix homelab Redis routing

OAuth login was silently failing: upsertUserSession() queried the
device_fingerprint column which didn't exist in the user_sessions
collection, PocketBase returned 400, the fallback authSessionId was
never written to the DB, and isSessionRevoked() immediately revoked
the cookie on first load after the OAuth redirect.

- scripts/pb-init-v3.sh: add device_fingerprint text field to the
  user_sessions create block (new installs) and add an idempotent
  add_field migration line (existing installs)

Audio jobs were stuck pending because the homelab runner was
connecting to its own local Redis instead of the prod VPS Redis.

- homelab/docker-compose.yml: change hardcoded REDIS_ADDR=redis:6379
  to ${REDIS_ADDR} so Doppler injects rediss://redis.libnovel.cc:6380
  (the Caddy TLS proxy that bridges the homelab runner to prod Redis)

homelab/docker-compose.yml

@@ -63,7 +63,7 @@ services:
       LIBRETRANSLATE_API_KEY: "${LIBRETRANSLATE_API_KEY}"
 
       # ── Asynq / Redis ─────────────────────────────────────────────────────
-      REDIS_ADDR: "redis:6379"
+      REDIS_ADDR: "${REDIS_ADDR}"
       REDIS_PASSWORD: "${REDIS_PASSWORD}"
 
       KOKORO_URL: "http://kokoro-fastapi:8880"

scripts/pb-init-v3.sh

@@ -196,6 +196,7 @@ create "user_sessions" '{
     {"name":"session_id",         "type":"text","required":true},
     {"name":"user_agent",         "type":"text"},
     {"name":"ip",                 "type":"text"},
+    {"name":"device_fingerprint", "type":"text"},
     {"name":"created_at",         "type":"text"},
     {"name":"last_seen",          "type":"text"}
   ]}'
@@ -291,5 +292,6 @@ add_field "app_users"      "oauth_id"               "text"
 add_field "app_users"      "polar_customer_id"      "text"
 add_field "app_users"      "polar_subscription_id"  "text"
 add_field "user_library"   "shelf"                  "text"
+add_field "user_sessions"  "device_fingerprint"     "text"
 
 log "done"