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)

scripts/pb-init-v3.sh

@@ -190,14 +190,15 @@ create "app_users" '{
     {"name":"oauth_id",              "type":"text"}
   ]}'
 
-create "user_sessions" '{
+ create "user_sessions" '{
   "name":"user_sessions","type":"base","fields":[
-    {"name":"user_id",   "type":"text","required":true},
-    {"name":"session_id","type":"text","required":true},
-    {"name":"user_agent","type":"text"},
-    {"name":"ip",        "type":"text"},
-    {"name":"created_at","type":"text"},
-    {"name":"last_seen", "type":"text"}
+    {"name":"user_id",            "type":"text","required":true},
+    {"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"}
   ]}'
 
 create "user_library" '{
@@ -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"