feat(auth): extend refresh TTL and keep session on transient errors

Bumps refresh token lifetime to 720h with env overrides, and stops
clearing the local session for non-401 refresh failures so users aren't
logged out by transient network blips. Adds a 60s retry timer when a
refresh fails for non-auth reasons.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/configs/config.local.yaml.example

@@ -127,6 +127,8 @@ object_storage:
 
 jwt:
   secret: "your-local-secret"
+  access_ttl: 15m
+  refresh_ttl: 720h
 
 llm:
   provider: ark

server/configs/config.yaml

@@ -137,7 +137,7 @@ cache:
 jwt:
   secret: "dev-secret-change-in-production"
   access_ttl: 15m
-  refresh_ttl: 168h
+  refresh_ttl: 720h
 
 log:
   level: debug,info,warn,error